Moldable and Molded Cellulosic Structural Materials, and Systems and Methods for Their Molding and Use

Abstract

Naturally occurring cellulosic materials, such as wood, bamboo, grass, or reeds, can be subjected to one or more chemical treatments to remove at least a portion of the lignin. The resulting partially delignified material can be partially or completely dried and then rehydrated to obtain a moldable cellulosic material. The moldable material can be molded from a substantially flat, planar configuration to a non-planar, three-dimensional configuration. After being molded into a desired shape, the moldable material can be completely dried to set the shape, thereby forming a rigid, molded piece. In some embodiments, the molded piece can be used as a structural material, for example, to form load-bearing structures and portions of composite load-bearing structures.

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 013,955, filed Apr. 22, 2020, entitled “Foldable, Structural Plant - Based Materials and Methods of Making, Folding, and Cutting the Same,” which is hereby incorporated by reference in its entirety.

[0002] The present invention generally relates to the processing of naturally occurring cellulosic materials, and more particularly to the shaping and use of fibrous plant - based materials to create formable pieces and formed structural materials.

Summary of the Invention

Problems to be Solved by the Invention

[0003] Embodiments of the subject matter described herein provide a “top-down” approach that can process wood or other fibrous plant materials (such as bamboo) into any three-dimensional (3D) shape while significantly increasing their mechanical strength. In some embodiments, the natural plant material is subjected to one or more chemical treatments (such as partial delignification) to remove at least some of the lignin. This can soften the natural plant material. Subsequently, by drying the partially delignified plant material, the conduits and fibers of the plant microstructure contract. In some embodiments, after drying, the material is “shocked” in a fluid (such as water) to selectively open the conduits. This rapid “fluid shock” process forms a unique partially open and wrinkled cell wall structure that provides space for compression and the ability to support high strains. This facilitates folding and shaping of the material. Alternatively, in some embodiments, the material is only partially dried, leaving the conduits substantially open. This enables folding and shaping of the material. The various shapes and structures that can be achieved using these formable plant materials are then set in place by further drying to remove the remaining fluid (for example, to have a moisture content of 15 wt% or less). This can form a rigid three-dimensional shaped plant structure.

[0004] In some embodiments, the cell wall processing process described herein can maintain the inherent anisotropic microstructure of the plant material and can enhance the interaction between the cellulose-based fibers within the cell wall. Such interactions can further enhance the mechanical properties of the processed plant material. Thus, in some embodiments, the partially delignified plant material can be shaped into a three-dimensional shape to form part of a structural material or a composite structural material. For example, in some embodiments, the honeycomb core material can be formed from veneer sheets (e.g., made by rotary cutting between rolls). The structural material obtained by combining the honeycomb core material and a support plate (such as an aluminum plate) can exhibit a tensile strength of 300 MPa or less similar to that of an Al alloy, but the density is only 0.75 g / cm 3 as follows and is of lower cost. According to one or more embodiments of the subject matter described herein, other three-dimensional structures and uses are also possible.

[0005] Any of the innovative technologies described herein can be combined or used individually. This specification is provided to introduce, in a simplified form, a selection of concepts that will be described in more detail in the following detailed description. This specification is not intended to identify the key features or essential features of the subject matter recited in the claims, nor is it intended to be used to limit the scope of the subject matter recited in the claims. The above-described and other objects, features, and advantages of the technology described herein will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0006] Embodiments of the present invention will be described below with reference to the accompanying drawings. The accompanying drawings are not necessarily drawn to scale. Some elements may be simplified or omitted to assist in the illustration of the basic features and explanations. In the figures, like reference numerals indicate like elements.

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Mode for Carrying Out the Invention

[0007] [General Precautions] In this specification, specific aspects, advantages, and novel features of the embodiments described in this specification are explained. The methods and systems of the present invention should not be construed as being limited in any way. The present invention is directed to all novel and non-obvious features and aspects of the various embodiments described herein, alone and in various combinations and sub-combinations with each other. The methods and systems are not limited to a particular aspect or feature or combination thereof. Also, the embodiments described in this specification do not require the presence of one or more specific advantages or the solution of a problem. The techniques in any embodiment or example can be combined with the techniques described in any one or more other embodiments or examples. In view of the many possible embodiments to which the principles of the techniques described herein can be applied, it should be noted that the embodiments shown in the figures are exemplary and do not limit the scope of the techniques described herein.

[0008] Some operations of the methods described in this specification are, for convenience, described in a particular sequential order, but it should be noted that these orders are subject to rearrangement unless it is explicitly stated by specific terms hereinafter that they are in a particular order. For example, operations described in a particular order may be performed in a rearranged order or simultaneously. Further, for the sake of simplicity, the accompanying drawings may not show various ways in which the methods described in this specification are combined with other methods. Also, in this specification, terms such as "provide" or "achieve" may be used to explain the methods described in this specification. These terms are a great abstraction of the actual operations performed. The actual operations corresponding to these terms may vary depending on the specific embodiments and can be easily identified by those skilled in the art.

[0009] It should be noted that the numerical ranges described in this specification refer to each discrete point within the range including the endpoints unless otherwise explicitly stated. Unless otherwise explicitly stated, all numerical values representing, for example, the number of components, molecular weight, ratio, temperature, and time used in this specification or the claims are modified by the term "about". Therefore, unless otherwise implicitly or explicitly indicated, or unless the context is appropriately understood by those skilled in the art to have a clearer structure, the numerical parameters described in this specification are approximate values that may depend on the desired characteristics and / or the detection limits in standard test conditions / methods known to those skilled in the art. When directly and explicitly distinguishing the embodiments of the present invention from the prior art described in this specification, the numerical values of the embodiments are not approximate values unless the term "about" is described. When the terms "substantially", "nearly", "about" or similar terms are explicitly used in combination with a specific value, they are intended to include numerical values within about 10% of that value unless otherwise explicitly stated.

[0010] Directions and other relative references may be used to facilitate the description of the principles set forth in the accompanying drawings and the present specification, but are not intended to be limiting. For example, certain terms such as "inner", "outer", "upper", "lower", "top", "bottom", "inside", "outside", "left", "right", "front", "rear", "back" may be used. These terms are used as appropriate to provide a degree of clarity when dealing with relative relationships, particularly with respect to the embodiments shown in the figures. However, these terms are not intended to imply absolute relationships, positions, and / or orientations. For example, with respect to an object, the "upper" portion can become the "lower" portion simply by turning the object over. Nevertheless, it remains the same part and there is no change to the object.

[0011] As used herein, the term "comprising" means "including", and the singular definite or indefinite articles (a, an, the) include plural elements as well, unless the context clearly dictates otherwise. The term "or" means a single one of the recited alternative elements, or a combination of two or more elements, unless the context clearly dictates otherwise.

[0012] Although there are alternatives to the various components, parameters, operating conditions, etc. described herein, those alternatives are not necessarily equivalent, nor do they necessarily mean that they function equivalently. Also, unless otherwise specifically stated, it does not mean that the alternatives are listed in a preferred order. Unless otherwise specifically stated, any of the groups defined below can be replaced or reverted from that state.

[0013] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the appropriate methods and materials are described below. These materials, methods, and examples are illustrative only and not intended to limit the invention. Other features of the subject matter described herein will be apparent from the following detailed description and claims.

[0014] [Glossary of Terms] The following explanations of specific terms and abbreviations are provided to facilitate the description of various aspects of the subject matter described herein and to assist those of ordinary skill in the art in the practice of the subject matter described herein.

[0015] "Naturally occurring cellulosic materials": A part of any photosynthetic eukaryote in the plant kingdom in its grown natural state (e.g., a cut portion via mechanical means or other means). In some embodiments, the naturally occurring cellulosic materials include wood (e.g., hardwood or softwood), bamboo (e.g., any bamboo of the subfamily Bambusoideae including, but not limited to, Moso bamboo, Phyllostachys vivax, Kuma bamboo, Madake, and Kurochiku), reeds (e.g., any of Phragmites australis, Arundo donax, Neyraudia reynaudiana, Phalaris arundinacea, Glyceria maxima, Calamagrostis species, Cyperus papyrus, Sparganium species, Typha species, Elegia tectorum, and Thamnochortus insignis), or grasses (e.g., species selected from the order Poales or the family Poaceae). Alternatively or additionally, in some embodiments, the naturally occurring cellulosic materials can be any type of fibrous plant consisting of lignin, hemicellulose, and cellulose, which has a microstructure with a larger diameter in a part of the lumen formed by cells than others.

[0016] "Longitudinal growth direction": The direction of growth from the root or the trunk, and the cellulose cells forming the cell wall of the plant are generally aligned in the longitudinal growth direction. In some cases, the longitudinal growth direction may generally be perpendicular and may correspond to the direction of the flow of transpiration of water. This is in contrast to the radial growth direction that can extend outward from the central part of the plant and be generally horizontal.

[0017] "Delignification": Removing a part (e.g., at least 0.1%) or almost all (e.g., less than 99%) of the naturally occurring lignin from a naturally occurring cellulose-based material. The lignin content in the cellulose-based material before and after delignification can be evaluated using techniques known in the art. This is described, for example, in the Laboratory Analytical Procedure (LAP) TP-510-42618 (version 08-03-2012) in "Determination of Structural Carbohydrates and Lignin in Biomass" issued by the National Renewable Energy Laboratory (NREL) of the United States, which is incorporated herein by reference, and in ASTM E1758-01 (2020) in "Standard Test Method for Determination of Carbohydrates in Biomass by High Performance Liquid Chromatography" issued by ASTM International.

[0018] "Moisture content": The amount of fluid, typically water, retained within the microstructure of a plant-based material. In some embodiments, the moisture content (MC) can be determined by an oven-dry test that calculates the change in weight obtained by oven-drying the plant-based material (e.g., at 103 °C for 6 hours). This can be obtained by the following formula.

[0019]

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[0020] Alternatively or additionally, the moisture content can be evaluated using techniques known in the art, such as an electronic moisture meter or other techniques. This is described, for example, in ASTM D4442-20(2020) in "Standard Test Methods for Direct Moisture Content Measurement of Wood and Wood-based Materials" published by ASTM International, which is incorporated herein by reference.

[0021] "Monolithic": A single continuous piece, as compared to a single piece formed by joining or combining (e.g., laminating) multiple small pieces.

[0022] Without fatigue: The ability to be repeatedly folded or bent without exhibiting material failure such as plastic deformation, formation of notches or creases, breakage, and fraying.

[0023] "Shaping": Bending, folding, pressing down, pressing, or non-destructively shaping a piece of material into a desired shape (e.g., without removing cellulose-based material).

[0024] Three-dimensional (3D) configuration: In contrast to a substantially flat planar configuration (where cellulose cells are substantially aligned along a common direction), a 3D configuration is such that at least one outer surface has a non-planar portion, or some of its cellulose nanofibers are not aligned with those of other portions, or the piece does not have an overall planar hexahedron shape, or any combination thereof, and a single monolithic piece is formed.

[0025] [Introduction] In embodiments of the present invention, the microstructure of naturally occurring cellulosic materials can be modified to provide the material with greater flexibility. This modification can include removing not all but a portion of the lignin from the natural material by one or more chemical treatments (e.g., partial delignification). In some embodiments, this modification substantially retains the cellulosic longitudinal cells of the microstructure of the natural material. However, sufficient lignin may be removed such that gaps are formed between adjacent cells. When the partially delignified material is dried after chemical treatment, the lumens of the cells of the microstructure contract or wrinkle therein. In some embodiments, the partially delignified material is completely dried (e.g., such that the moisture content is 15 wt% or less), and the lumens are substantially collapsed. After drying, the partially delignified material can be rehydrated by partially or fully immersing it in a fluid for a short period (e.g., less than 5 minutes). The rehydrated material is more flexible than the natural material. Alternatively, in some embodiments, the partially delignified material is partially dried (e.g., such that the moisture content is 35 wt% or more), and at least some of the lumens are collapsed or shrunk. Also, the partially dried material may be more flexible than the natural material.

[0026] In some embodiments, the more flexible, i.e., formable, cellulosic material can optionally be formed, for example, by folding, bending, using compression molds, or any other technique. In some embodiments, the formable cellulosic material may first be provided as a thin flat piece having a thickness of, for example, 10 mm or less. The formable material can then be folded, bent, or otherwise formed in any direction, at any position, and at any angular orientation (e.g., 0 to 180 ° (including both ends)) to form any complex three-dimensional structure. For example, in some embodiments, the formable cellulosic material can be cut and / or folded to create complex three-dimensional structures, similar to origami and / or paper cutting.

[0027] As long as the cellulosic material retains a sufficient fluid content (e.g., a moisture content of 35 wt% or more), the material can maintain formability / flexibility. By completely drying a material configured to have a particular shape (e.g., such that the moisture content is 15 wt% or less), the material is “set” to retain the shape. Thereby, a rigid formed structure that plastically deforms by further forming can be formed. The resulting formed material has enhanced mechanical properties compared to the original natural material. For example, in some embodiments, the formed material is a rigid monolithic piece that can be used as a structural material or integrated with other materials to form a composite structural material. Alternatively, in some embodiments, the formable material may be maintained in a hydrated state to maintain its flexibility for use as a flexible substrate or other support structure.

[0028] The engineering approach to cell walls described herein can fundamentally expand the capabilities of natural plant materials (such as wood, bamboo, grass, etc.) as lightweight structural materials from conventional planar structures to more versatile complex three-dimensional designs and components.

[0029] [Examples of Methods] FIG. 1 shows an exemplary method 100 for forming a formable structure from a naturally occurring cellulosic material and subsequent uses thereof. In some embodiments, the plant material is wood, bamboo, grass, or reed. However, in other embodiments, the plant material can be any type of fibrous plant consisting of lignin, hemicellulose, and cellulose. This has a microstructure in which the diameter of some lumens formed by cells is larger than others. For example, the microstructure of a naturally occurring cellulosic material can have a first lumen formed by the wall of a first longitudinal cell (such as a fiber, microfibril, or tracheary element) and having a first cross-sectional size, and a second lumen formed by the wall of a second longitudinal cell (such as a vessel) and having a second cross-sectional size larger than the first cross-sectional size.

[0030] The method 100 can start at process block 102. Here, fragments of natural cellulosic materials are prepared. For example, the preparation at process block 102 can include cutting, removing, or separating fragments of natural cellulosic materials from the parent plant. In some embodiments, by cutting, the cellulosic material can be formed into a substantially flat planar structure. Here, the direction of the cellulose fibers extends parallel to the plane of the structure. Optionally, in some embodiments, the preparation can include pretreatment of the fragments of natural cellulosic materials. For example, washing to remove undesirable materials or contaminants in preparation for subsequent processing, shaping the natural cellulosic material into a specific shape (such as slicing it into strips) in preparation for subsequent processing, softening or flattening the cellulosic material (e.g., using steam treatment), or any combination thereof.

[0031] In process block 104, the cellulosic material is subjected to one or more chemical treatments, for example, by immersing the natural cellulosic material (or a part thereof) in a chemical solution related to the treatment, so that at least a part of the lignin is removed therefrom. In some embodiments, each chemical treatment or only some of the chemical treatments can be carried out under vacuum to promote complete penetration of the solution related to the treatment into the cell walls and lumens of the natural cellulosic material. Alternatively, in some embodiments, the chemical treatment can be carried out under ambient pressure conditions or elevated pressure conditions (e.g., 6 to 8 bar or less). In some embodiments, each chemical treatment or some of the chemical treatments can be carried out at any temperature between ambient temperature (e.g., 23°C or less) and a high temperature at which the solution related to the chemical treatment boils (e.g., 70°C to 160°C or less). In some embodiments, to minimize damage to the microstructure of the natural cellulosic material, the solution is not agitated.

[0032] In some embodiments, the immersion time can range from 0.1 hour to 96 hours, for example, it can range from 4 hours to 12 hours (including both ends). The immersion time in the solution may be a function of the amount of lignin to be removed, the size of the fragments, the temperature of the solution, the pressure of the treatment, and / or agitation. For example, less lignin removal amount, smaller fragment size, higher solution temperature, higher treatment pressure, and agitation may be associated with a shorter immersion time, and more lignin removal amount, larger fragment size, lower solution temperature, lower treatment pressure, and no agitation may be associated with a longer immersion time.

[0033] In some embodiments, the solution for chemical treatment includes an alkaline solution. In some embodiments, the solution for chemical treatment is sodium hydroxide (NaOH), lithium hydroxide (LiOH), potassium hydroxide (KOH), sodium sulfite (Na2SO3), sodium sulfide (Na2S), Na n S (where n is an integer), urea (CH4N2O), sodium bisulfite (NaHSO3), sulfur dioxide (SO2), anthraquinone (AQ) (C 14 H8O2), methanol (CH3OH), ethanol (C2H5OH), butanol (C4H9OH), formic acid (CH2O2), hydrogen peroxide (H2O2), acetic acid (CH3COOH), butyric acid (C4H8O2), performic acid (CH2O3), peracetic acid (C2H4O3), ammonia (NH3), p-toluenesulfonic acid (p-TsOH), sodium hypochlorite (NaClO), sodium chlorite (NaClO2), chlorine dioxide (ClO2), chlorine (Cl2), or any combination thereof. Exemplary combinations of chemicals for chemical treatment are NaOH + Na2SO3, NaOH + Na2S, NaOH + urea, NaHSO3 + SO2 + H2O, NaHSO3 + Na2SO3, NaOH + Na2SO3, NaOH + AQ, NaOH + Na2S + AQ, NaHSO3 + SO2 + H2O + AQ, NaOH + Na2SO3 + AQ, NaHSO3 + AQ, NaHSO3 + Na2SO3 + AQ, Na2SO3 + AQ, NaOH + Na2S + Na nS (where n is an integer), and can include, but is not limited to, Na2SO3 + NaOH + CH3OH + AQ, C2H5OH + NaOH, CH3OH + HCOOH, NH3 + H2O, and NaClO2 + acetic acid.

[0034] The chemical treatment can be continued (or repeated in a subsequent solution) until the lignin content of the natural cellulosic material is reduced to the desired amount. The lignin content can be reduced in the range of 0.1% (the lignin content is 0.1% of the original lignin content of the natural cellulosic material) to 99% (the lignin content is 99% of the original lignin content of the natural cellulosic material), depending on the desired application. For example, in some embodiments where it may be desirable to retain as much of the natural cellulosic material as possible, the reduction in lignin content can be relatively small, such that the lignin content is reduced to not exceed 10% compared to the original lignin content of the natural cellulosic material. In some embodiments, more lignin can be removed such that at least 90% of the original lignin content is removed (e.g., 90% - 100% of the lignin is removed). In some embodiments, the lignin content is reduced by 50% or less compared to the original lignin content of the natural cellulosic material. In some embodiments, the chemical treatment reduces the hemicellulose content, for example, to the same extent or less than the amount by which the lignin content is reduced, simultaneously with the reduction in lignin content.

[0035] In some embodiments, when the natural cellulosic material is hardwood, the lignin content after delignification in process block 104 can be at least 10 wt% (e.g., in the range of 10 wt% to 15 wt% (including both ends)). In some embodiments, when the natural cellulosic material is softwood, the lignin content after delignification in process block 104 can be at least 12.5 wt% (e.g., 12.5 wt% to 17.5 wt% (including both ends)). In some embodiments, when the natural cellulosic material is bamboo, the lignin content after delignification in process block 104 can be at least 13 wt% (e.g., 13 wt% to 18 wt% (including both ends)). By removing lignin from the natural plant material, the cell lumen can be expanded and the hydrophilicity can be improved.

[0036] In some embodiments, process block 104 can further include an optional rinsing step after the chemical treatment, for example, to remove residual chemicals or particulates resulting from the delignification process. For example, the delignified cellulosic material can be partially or fully immersed in one or more rinsing solutions. The rinsing solution can be a solvent such as deionized (DI) water, alcohol (ethanol, methanol, isopropanol, etc.), or any combination thereof, but is not limited thereto. For example, the rinsing solution can be formed of equal volumes of water and ethanol. In some embodiments, the rinsing can be performed without agitation, for example, to avoid disruption of the microstructure. In some embodiments, the rinsing can be repeated multiple times (e.g., at least 3 times) while using a fresh mixed rinsing solution each time.

[0037] The method 100 can proceed to decision block 106. Here, it is determined whether the fluid impact method is to be implemented. If it is determined that the fluid impact is not implemented, the method 100 can proceed from decision block 106 to process block 108. Here, the partially delignified cellulosic material is partially dried. For example, the partial drying in process block 108 is carried out such that the cellulosic material has a moisture content of at least 35 wt% (e.g., 50 wt% or more). Also, if it is determined that the fluid impact is not implemented, the method 100 can proceed from decision block 106 to process block 110. Here, the partially delignified cellulosic material is completely dried. For example, the complete drying in process block 110 is carried out such that the cellulosic material has a moisture content of 15 wt% or less (e.g., about 8 wt% to about 12 wt% (including both ends)).

[0038] Drying in process block 108 or process block 110 can include any of conduction, convection, and / or radiation heating processes including, but not limited to, air drying processes, vacuum-assisted drying processes, oven drying processes, freeze drying processes, critical point drying processes, microwave drying processes, or any combination thereof. For example, an air drying process can include naturally drying a partially delignified cellulosic material in static or moving air. Here, the air can be at any temperature, such as room temperature (e.g., 23 °C) or higher than that (e.g., above 23 °C). For example, a vacuum-assisted drying process can include exposing a partially delignified cellulosic material to a reduced pressure of less than, for example, 1 bar, in, for example, a vacuum chamber or a vacuum oven. For example, an oven drying process can include heating a partially delignified cellulosic material at a high temperature (e.g., above 23 °C), for example, 70 °C or higher, using an oven, a hot plate, or other conduction, convection, or radiation heating device. For example, a freeze drying process can include lowering the temperature of a partially delignified cellulosic material below the freezing point of the fluid therein (e.g., below 0 °C) and reducing the pressure to sublimate the frozen fluid therein (e.g., less than a few millibars). For example, a critical point drying process can include immersing a partially delignified cellulosic material in a fluid (e.g., liquid carbon dioxide), increasing the temperature and pressure of the bamboo segment beyond the critical point of the fluid (e.g., 7.39 MPa, 31.1 °C for carbon dioxide), and then gradually releasing the pressure to remove the gasified fluid. For example, a microwave drying process can include inducing dielectric heating in a partially delignified cellulosic material by exposing it to electromagnetic radiation having a frequency in the microwave region (e.g., 300 MHz to 300 GHz), for example, a frequency of 915 MHz or less or 2.45 GHz or less, using a microwave oven or other microwave generating device.

[0039] In some embodiments, due to complete drying in process block 110, the delignified cellulosic material shrinks, causing significant buckling in the cell walls. In some embodiments, the lumens formed by longitudinal cells may collapse (e.g., completely collapse so that the opposing surfaces of the channel walls contact each other or at least become significantly narrower). After drying in process block 110, the method 100 can proceed to process block 112. Here, the fluid impact method is used to rehydrate the dried cellulosic material. For example, the dried cellulosic material can be partially or completely immersed in a fluid (e.g., water, alcohol, or any combination thereof) for a short time (e.g., several minutes in seconds of 3 minutes or less) such that the rehydrated material has a moisture content of at least 35 wt% (e.g., about 50 wt%). According to one or more embodiments, methods for rehydration other than immersion in a fluid are also possible. For example, rehydration can be achieved by exposing to a humidified environment.

[0040] In some embodiments, rehydration is effective to re-expand the cell walls and open larger lumens (such as a second lumen formed by a second longitudinal cell) while leaving smaller lumens (such as a first lumen formed by a first longitudinal cell) substantially collapsed. The expansion introduced by fluid impact can cause wrinkles in the cell wall structure. This enables the cellulosic material to withstand severe tension and compression without damage.

[0041] After process block 108 or process block 112, with the cellulosic material having a moisture content of at least 35 wt%, the method 100 can proceed to decision block 114. Here, it is determined whether pre-forming modification is desirable. If such modification is desirable, the method 100 can proceed to process block 116. Here, a non-machining method (e.g., one that does not remove a large amount of material for modification) is used to form holes, openings, recesses, or other surface modifications. The modification can be performed while the moisture content of the partially delignified cellulosic material is at least 35 wt% and in a substantially flexible / formable state. As a result, the cellulose fibers can retain sufficient mobility to bend around the formation of holes, openings, or recesses without breaking.

[0042] After the modification in process block 116, or if it is determined in decision block 114 that modification is not desirable, the method 100 can proceed to process block 118. Here, the cellulosic material is formed to have a desired configuration such as a three-dimensional configuration. The forming in process block 118 can include bending, folding, pressing (e.g., using a mold), or non-destructively forming (e.g., without removing material) the sub-material so that the partially delignified cellulosic material has the desired configuration. During forming, since the moisture content of the partially delignified cellulosic material is at least 35 wt%, it is in a substantially flexible / formable state. As a result, the partially delignified cellulosic material can easily adopt the formed configuration and return to its original pre-formed configuration without damage.

[0043] The method 100 can proceed to decision block 120. Here, it is determined whether the partially delignified cellulosic material should be set to a formed configuration or whether the partially delignified cellulosic material should be maintained in a flexible / formable state. If it is desirable to maintain the cellulosic material as a formable material, the method 100 can proceed to process block 122. Here, its moisture content is maintained at 35 wt% or more. If it is desirable to set the cellulosic material to a formed configuration, the method 100 can proceed to process block 124. Here, the cellulosic material is completely dried while maintaining the formed configuration such that the moisture content is reduced to 15 wt% or less. The drying in process block 124 may be carried out in the same manner as described above with respect to process block 110. Alternatively or additionally, in some embodiments, the drying can be a byproduct of the forming that occurs, for example, by using heat pressing to simultaneously form and dry the formable cellulosic material. In such embodiments, the forming can be effective to further densify the cellulosic material before it is completely dried. This densification may be able to further improve the mechanical properties of the formed material. The completely dried partially delignified cellulosic material is rigid and further forming without plastic deformation is not possible. Thereby, a formed structure is formed.

[0044] In some embodiments, the method 100 can proceed from process block 122 or process block 124 to process block 126. Here, external modifications can optionally be applied. For example, the cellulosic material can be sealed to prevent the entry or exit of moisture and maintain the material in a desired moldable state (e.g., a flexible state) or a molded state (e.g., a rigid state). In some embodiments, the sealing is performed by placing the cellulosic material in a sealed or controlled environment. Alternatively or additionally, the sealing can be achieved by a protective layer or coating provided on the exposed surface of the cellulosic material. For example, the protective layer or coating can be a polyurethane coating, a paint, a silane hydrophobic coating, or any other coating effective in preventing or at least restricting the movement of moisture into and out of the cellulosic material. Alternatively or additionally, the external modifications can include, for example, destructive modifications such as machining or cutting to prepare the cellulosic material for subsequent use.

[0045] The method 100 can proceed to process block 128. Here, the partially delignified cellulosic material in a moldable or molded state can be used for a specific application or adapted for use in a specific application. In some embodiments, the molded partially delignified cellulosic material can be used as a structural material, for example, assembled with non-vegetable materials (such as metals, metal alloys, plastics, ceramics, composite materials, etc.) to form a heterogeneous composite structure. Alternatively, in some embodiments, the moldable partially delignified cellulosic material can be used as a flexible substrate or structure, for example, as a skeleton for robotic operation or a substrate for electronic devices.

[0046] Although part of blocks 102 to 128 of the method 100 has been described as being performed once, in some embodiments, multiple repetitions of a particular process block can be employed before proceeding to the next decision block or process block. Also, although blocks 100 to 128 of the method 100 have been illustrated and described individually, in some embodiments, process blocks can be combined and performed together (simultaneously or sequentially). For example, as described above, drying in process block 124 and shaping in process block 118 can be performed simultaneously. Further, although FIG. 1 shows a particular order of blocks 102 to 128, in embodiments of the subject matter described herein, it is not limited thereto. In fact, in certain embodiments, the blocks may be performed in an order different from that shown in the figures or simultaneously with other blocks. For example, the modification in process block 116 can be performed after the shaping in process block 118 while the partially delignified cellulosic material remains in a formable state.

[0047] [Realization with wood] As shown in the exemplary portion 212 of the hardwood shown in FIGS. 2B to 2C, natural wood has vessels 214 that extend in the growth direction 210 of the wood (e.g., having a maximum cross-sectional dimension, i.e., diameter, in a plane perpendicular to its length of 40 μm to 80 μm (including both ends)), and fibers 216 (e.g., having a maximum cross-sectional dimension, i.e., diameter, in a plane perpendicular to its length of 10 μm to 30 μm (including both ends)), and has a unique three-dimensional porous structure having a plurality of channels or lumens formed by longitudinal cells. The cell walls of natural wood mainly consist of cellulose (40 wt% to 50 wt%), hemicellulose (20 wt% to 30 wt%), and lignin (20 wt% to 35 wt%), and these three components are intertwined with each other to form a strong and rigid wall structure. Naturally occurring cellulose exhibits a layered structure. For example, as shown in FIG. 2D, the cells 218 of natural wood have a plurality of cellulose fibers 220 surrounding the lumen 216, which extend substantially parallel to the lumen 216. The cellulose fibers 220 can be separated into corresponding high aspect ratio microfibrils 222 in the form of an aggregated (e.g., as a bundle) three-dimensional network that provides a relatively high surface area. The cellulose microfibrils 222 can be further subdivided into elementary nanofibrils 224 composed of 12 to 36 linear polymer molecular chains 226. Each polymer molecular chain 226 is formed of thousands of repeating glucose units connected by strong covalent bonds, which are arranged in a highly ordered crystal structure. The polymer molecular chains 226 are held in a high-density arrangement forming the elementary nanofibrils 224 by intermolecular hydrogen bonds between the functional groups of adjacent molecular chains.

[0048] Fragments of natural wood can be cut in any direction with respect to its longitudinal growth direction 210. Since the cellulose fibers 218 are naturally aligned in the growth direction, the cutting direction determines the direction of the cell lumens in the final structure. This direction can affect the mechanical properties of the final formable or formed wood structure. For example, in some embodiments, a fragment of natural wood is cut perpendicular or longitudinally (e.g., parallel to the longitudinal wood growth direction 210) from the trunk 202 of the tree 200 such that the longitudinal cell lumens are oriented substantially parallel to the major face (e.g., the largest surface area) of the wood fragment 206 where the longitudinal cell lumens are cut longitudinally. Alternatively, in some embodiments, a fragment of natural wood is cut horizontally or radially (e.g., perpendicular to the longitudinal wood growth direction 210) such that the longitudinal cell lumens are oriented substantially perpendicular to the major face of the wood fragment 204 where the longitudinal cell lumens are cut horizontally. Alternatively, in some embodiments, a fragment of natural wood is cut in a rotational direction (e.g., a direction perpendicular to the longitudinal wood growth direction 210 and along the circumferential direction of the trunk 202) such that the longitudinal cell lumens are oriented substantially parallel to the major face of the wood fragment 208 where the longitudinal cell lumens are cut rotationally. In some embodiments, a fragment of natural wood can be cut in any other direction between longitudinal, radial, and rotational cuts. For any cutting direction, the thickness of the fragment of natural wood can be measured in a direction perpendicular to the major face and can be 10 mm or less.

[0049] Referring to FIG. 4A, various stages in forming a formable fragment of wood using fluid impact processing are shown. As described above, natural wood 402 has conduits 404 and fiber cells 408 composed of cellulose, hemicellulose, and lignin. In particular, the cell walls forming lumens 406 and 410 extending in the longitudinal growth direction of the wood 402 exhibit a composite structure 416 in which cellulose fibrils 412 are bonded by a hemicellulose and lignin adhesion matrix 414. This is excellent in strength and rigidity. To obtain a foldable structure, the natural wood 402 in the initial stage 400 is subjected to a delignification process 418 via one or more chemical treatments. The lignin removal efficiency by chemical treatment can depend on factors such as the size of the wood, the chemical treatment time, temperature, and chemical treatment conditions (e.g., under vacuum or pressure), and / or the choice of chemicals. For example, to reduce the lignin content of the wood to 55% or less and the hemicellulose content to 67% or less, the natural wood 402 can be partially or completely immersed in a boiling solution of NaOH and Na2SO3 for 6 hours, and then one or more rinsing or washing solutions can be used. For example, when the natural wood is hardwood, the wood fragment 402 in stage 400 can have a composition of 45.1 wt% cellulose, 18.7 wt% hemicellulose, and 21.3 wt% lignin. After delignification 418, the delignified wood fragment 422 in stage 420 can have a composition of 40.1 wt% cellulose, 6.1 wt% hemicellulose, and 9.5 wt% lignin.

[0050] Partial removal of the hydrophobic lignin component (residual lignin 434 intertwines between microfibrils 412) results in the cell wall 436, characterized by a high proportion of hydrophilic cellulose, absorbing water 438, causing the size of the wood to soften and gently expand. Thus, the delignified wood 422 has thinner walls of the conduits 424 and fibers 428 due to partial removal of lignin and hemicellulose, while the cross-sectional sizes of the lumens 426 and 430 increase. Furthermore, partial delignification causes the cell walls to separate 432 from each other. This also contributes to the volume expansion of the wood. For example, the moisture content of the partially delignified wood 422 can be 75 wt% or less, and the volume of the delignified wood 422 can be 14% - 20% larger than the volume of the original natural wood 402.

[0051] After delignification 418, the partially delignified wood 422 is dried 439 until its moisture content becomes less than 15 wt% (e.g., 8 wt% - 12 wt%). The dried wood 442 obtained at stage 440 can have a shrunk shape, for example, due to evaporation of water from the cell wall. From the perspective of the microstructure, the dried conduit 446 shrinks such that the lumen 444 is about 1.5 μm along the transverse direction (T) of the wood and about 13.6 μm along the radial direction (R) of the wood. On the other hand, the smaller-sized fibers 448 in the dried wood 442 can have a dimension of approximately 0 μm along the T direction and a dimension of 9.6 μm along the R direction, and can be in a substantially crushed state. As a result, the microstructure of the dried wood shows a large deformation space in the T and R directions, for example, such that the volume of the dried wood 442 is 59% - 63% less than the volume of the partially delignified wet wood 422 at stage 420. On the other hand, within the cell wall 456, adjacent microfibrils 412 can be aggregated by the capillary effect of water evaporation, and hydrogen bonds 450 can be formed in the cellulose of the microfibrils 412.

[0052] After drying 439, the dried wood 442 is rehydrated using fluid impact treatment 458 until its moisture content exceeds 35 wt% (e.g., 50 wt% or more). The formable wood 462 obtained at stage 460 can expand for water reabsorption. For example, the volume of the formable wood 462 can increase by 67.6% compared to the dried wood 442. Here, the volume of the formable wood 462 may be smaller than the volume of the original natural wood 402. From the perspective of its microstructure, due to the fluid impact treatment, the lumen 464 of the larger-sized conduits 466 has a more wrinkled and flexible configuration compared to the original conduits 404, but is expanded and at least partially open. During the fluid impact treatment 458, the reopening of the conduits 466 can occur rapidly (e.g., in seconds such as 3 seconds), while the morphology of the smaller fibers 468 changes relatively little during the treatment time (e.g., in minutes such as 3 minutes). On the other hand, the smaller fibers 468 remain substantially closed despite rehydration. Such selective opening of the cell wall microstructure can provide the following two simultaneous effects: (1) The partially open conduits form spaces within the formable wood 462 that can accommodate deformations in both compression and tension, and can be folded like an "accordion" while undergoing severe compression and tension (e.g., up to 180 ° degrees without breaking), (2) The high-density substantially closed fibers 468 can provide mechanical support for strengthening the strength. Within the cell wall 476, the reintroduction of water 470 can break the hydrogen bonds 450 that interconnected the cellulose microfibrils 412 in the dry state. This allows the microfibrils to move more easily relative to each other.

[0053] The moisture content can have a significant impact on the elastic modulus and strain of the formable wood 462. For example, when the moisture content is 100%, the formable wood 462 may have an elastic modulus that is 92 times lower and a strain along the T direction that is 8.8 times higher compared to the dry wood 442 with a moisture content of only 10 wt%. Thus, the delignified wood can be substantially changed from a rigid state to a flexible / formable state simply by changing the moisture content. At higher moisture contents (e.g., above 25% - 35 wt%), this change in the elastic modulus enables excellent folding ability.

[0054] The folding ability does not depend solely on the moisture content. Rather, the folding ability of the formable wood 462 is due to a cooperative effect resulting from the spatial shrinkage introduced by drying and the fluid lubrication introduced by rehydration. Therefore, in the case of wet natural wood 402 with sufficient moisture content but no shrinkage / crinkling of the microstructure, the wood 402 cannot be bent without breaking. Similarly, in the case of dry wood 442 with shrinkage / crinkling of the microstructure but insufficient moisture content, the wood 442 cannot be bent without breaking. However, since the formable wood 462 has both shrinkage / crinkling of the microstructure and sufficient moisture content, the wood 462 can be easily folded without breaking.

[0055] In some embodiments, similar effects can be obtained by replacing the drying and fluid impact treatment in FIG. 4A with partial drying. For example, FIG. 4B shows various stages in forming a formable piece of wood using partial drying instead of fluid impact treatment. Delignification 418 of natural wood 402 can occur as described above with respect to FIG. 4A. However, instead of completely drying the partially delignified wood 422 after step 420, the wood 422 is partially dried 478 until its moisture content is reduced but remains at 35 wt% or more (e.g., 50 wt% or less). Thus, the partially dried wood 482 obtained at step 480 can have a similar microstructure. Here, the lumen 486 of the conduit 484 remains at least partially open with a wrinkled cell wall, and the smaller fibers 488 are substantially crushed or at least narrowed. Further, the water 438 retained within the cell wall 496 can act to provide the lubricity necessary for flexibility. Thus, the partially dried wood 482 can exhibit excellent folding ability and can be considered formable wood.

[0056] The formable wood 462 or 482 obtained from these cell wall engineering techniques can be processed into various shapes by mechanical bending, folding, and twisting. Once the desired configuration is obtained, the formable wood 462 or 482 is dried and set or fixed in that shape. This forms a substantially rigid (e.g., cannot be further processed without plastic deformation or breakage) formed final wood structure. The excellent folding ability of the formable woods 462 and 482 and the excellent stability of the formed wood after drying provide the possibility to design and manufacture complex three-dimensional shapes, for example, as part of independent structural materials or composite structural materials.

[0057] [Realization with Bamboo] In the above description, the focus was on wood, but other fibrous plant materials having longitudinal cells that form lumens of different sizes can also be processed to obtain the same effect. For example, bamboo can be processed in the same manner as described above for wood to obtain formable, partially delignified bamboo.

[0058] Figure 3A is a partial cross-sectional view of a naturally occurring bamboo segment 300. The segment 300 has a culm wall 302 surrounding a hollow internal region 316. The internal region 316 is divided into internal node regions 312 along the length of the culm wall 302 by nodes 308 formed by nodal diaphragms 310. The culm wall 302 has fibers extending along a longitudinal direction 328 (e.g., a direction substantially parallel to the growth direction of the bamboo or the axis defined by the hollow internal region 316 of the bamboo segment 300) embedded in a matrix of lignin. One or more branch portions 314 can extend from a particular internal node region 312 and can serve as a root from which a culm wall for a new bamboo segment can grow (thereby, for example, defining a different longitudinal direction for the new segment).

[0059] Within the culm wall 302, bamboo exhibits a hierarchical cell structure that includes porous cells that provide hierarchical cell structure nutrient transport and high-density cells that provide mechanical support. For example, FIGS. 3B-3D show cross-sections of the bamboo segment 300 and, in particular, the microstructure of the parenchyma cells 322, vessels 324, and fiber bundles 326 that make up the culm wall 302. The fiber bundles 326 are highly aligned and extend substantially parallel to the longitudinal direction 328, and the parenchyma cells 322 can extend parallel or perpendicular to the longitudinal direction 328. Each vessel 324 defines an open lumen that extends along the longitudinal direction 328. Further, the elementary fibers that form the fiber bundles 326 may have irregularly small lumens at their centers. The fiber bundles 326, parenchyma cells 322, and vessels 324 are adhered to each other via a low-strength polymer matrix composed of lignin and hemicellulose.

[0060] Similar to the wood examples, partial delignification of the bamboo 300 allows water to be absorbed by each cell wall, causing the bamboo to soften and its size to gently expand. In this way, the corresponding lumens of the cells can be enlarged. In some embodiments, the partially delignified bamboo in which the lumens of the conduits and the elementary fibers contract is completely dried (e.g., moisture content of 15 wt% or less), and then the bamboo can be rehydrated via a fluid shock method to selectively open the lumens of the conduits while the lumens of the fibers remain substantially closed or at least narrowed (e.g., moisture content of 35 wt% or more). Thereby, formable bamboo is realized. Alternatively, in some embodiments, the partially delignified bamboo is partially dried (e.g., moisture content of 35 wt% or more). Thereby, formable bamboo is realized.

[0061] [Forming Example] Referring to FIGS. 5A - 5C, the formable, partially delignified cellulosic material 502 can be folded to obtain a desired three - dimensional configuration. Thereafter, the formable material can be dried to set the configuration. Thereby, a rigid, formed structure is created. For example, the microstructure of the cellulosic material 502 can include open conduits 506 and substantially collapsed fiber cells 508 that each extend along the longitudinal growth direction 504 of the natural plant. The cellulosic material 502 can have a thickness t of 10 mm or less in a direction perpendicular to the longitudinal growth direction 504. The formable material 502 can be bent or folded in any direction in a plane perpendicular to the thickness direction. The formable material 502 is 180 °It can be folded or bent through an angle 520. For example, when the first portion 524 and the second portion 526 of the formable material 502 are bent or folded relative to each other about the fold line 522, as shown in FIG. 5C, the material 502 has an interior angle 528 (e.g., the angle between the first portion 524 and the second portion 526 of the material 502) and an exterior angle 530 (e.g., the supplementary angle to the interior angle 528 formed between the original position of the bent or folded portion and the final position of the bent or folded portion). The interior angle 528 is 0 ° (e.g., in a state where the first portion 524 and the second portion 526 are in contact) to 180 ° can be in the range of.

[0062] FIGS. 5B - 5C show the state of being folded about a fold line perpendicular to the longitudinal growth direction 504, but the embodiments of the subject matter described herein are not limited thereto. Rather, as shown in FIG. 5A, the material 502 can be folded or bent about a direction 512 perpendicular to the longitudinal growth direction 504, a direction 516 parallel to the longitudinal growth direction 504, a direction 514 or 518 at 45° to the longitudinal growth direction 504, or any direction between 512 - 518. Further, the formable cellulose - based material can be folded and unfolded multiple times without breakage or deformation (e.g., operation without fatigue) as long as it retains a sufficient moisture content (e.g., 35 wt% or more).

[0063] In some embodiments, the formable cellulose-based material can be folded one or more times, similar to origami or paper cutting, to create a three-dimensional structure. For example, FIGS. 6A - 6L show various folding patterns that can be employed with the formable cellulose-based material, such as the half-fold pattern 602, the three-fold pattern 604, the four-fold pattern 606, the scroll four-fold pattern 608, the double-scroll four-fold pattern 610, the open-kwan-yin fold pattern 612, the kwan-yin tuck pattern 614, the Z-fold pattern 616, the accordion fold pattern 618, the stash fold pattern 620, the Turkish fold pattern 622, and the Miura fold pattern 624. Also, patterns other than those shown in the figures are possible. Furthermore, by combining basic folding patterns, a formable cellulose-based material with a more complex structure can be formed.

[0064] Alternatively, in some embodiments, the formable cellulose-based material can be bent (e.g., to have a radius of curvature) to form a three-dimensional structure. For example, FIG. 7A shows a formable cellulose-based material 700 bent to form arcuate or curvilinear portions 702 rather than discrete creases or fold lines. FIG. 7B shows another example where the formable cellulose-based material is wrapped around a rod and dried, thereby forming a shaped cellulose-based material 704 having a cork-like or helical configuration around a central axis 706. In another example, a multilayer cylinder can be created by roll-forming and drying the formable cellulose-based material. Other more complex shapes can be formed by any combination of bending and folding. Whether by bending, folding, twisting, molding, or other shaping, the formable cellulose-based material can be converted into a rigid, shaped structure by drying the material in the desired configuration.

[0065] [Examples of Structural Materials] In some embodiments, the formable cellulose-based material can be folded, bent, or shaped into a suitable three-dimensional configuration and then dried to set the configuration. Such three-dimensionally formed cellulose-based materials can serve as components of structural materials or composite structural materials. For example, FIG. 8 shows an exemplary repeating undulating configuration of a cellulose-based material as a structural material or a component thereof. This undulating or wavy structural material 800 can be formed from a single monolithic piece of the formable cellulose-based material. After folding the formable material to have the configuration shown in the figure, the formable material can be dried to increase the rigidity of the material and set the shape.

[0066] The undulating structural material 800 is formed from a repeating pattern of upper peak regions 810 with intervening valley regions 814. Only two peak regions 810 and a single valley region 814 are shown in FIG. 8, but embodiments of the present invention can include dozens, hundreds, thousands, or more peak regions 810 and valley regions 814, respectively. Each peak region 810 is defined by an upper member 806 that is substantially flat or planar and is located between an upwardly inclined member 804 and a downwardly inclined member 808. Each valley region 814 is defined by a lower member 802 that is substantially flat or planar and is located between a downwardly inclined member 808 and an upwardly inclined member 804. The valley region 814 may be considered to share the upwardly inclined member 804 and the downwardly inclined member 808 with adjacent peak regions 810. The upper member 806 and the lower member 802 are shown in the figure as substantially flat or planar with distinct boundaries between different members 802 - 808, but actual embodiments may have rounded or gradually transitioning portions between different members, or non-planar configurations. The material 800 can be configured such that the formation of a peak region 810 on one side of the material forms a corresponding valley region on the opposite side of the material, and vice versa.

[0067] The undulating pattern shown in FIG. 8 can be formed by folding or bending a formable cellulosic material at the appropriate fold lines that form the joints between the upwardly inclined member 804 and the adjacent lower member 802 and upper member 806, as well as at the fold lines that form the joints between the downwardly inclined member 808 and the adjacent lower member 802 and upper member 806. In some embodiments, the fold lines forming such joints may extend parallel to the longitudinal growth direction of the natural plant. In such a configuration, the resulting formed material can be arranged to support loads in a direction parallel to the fold lines, for example, loads applied directly or indirectly to the exposed edges of members 802-808. Alternatively, in some embodiments, the fold lines forming such joints may extend perpendicular to the longitudinal growth direction of the natural plant. In such a configuration, the resulting formed material can be arranged to support loads in a direction perpendicular to the fold lines, for example, loads applied directly or indirectly to the lower member 802 and / or the upper member 806.

[0068] To form a shaped cellulose-based material having the undulating pattern of FIG. 8, batch manufacturing equipment employing a press mold can be used. For example, FIG. 9 shows an exemplary manufacturing facility employing batch operation. For example, a formable cellulose-based material 904 can be placed in batch equipment 900 (e.g., a hydraulic press) between an upper mounting plate 902a and a lower mounting plate 902b of a mold having a desired undulating pattern. In the pressing step 910, the upper and lower mounting plates can be brought together to press the formable cellulose-based material 904 therebetween. Thereby, the material 904 can be folded or bent into a desired undulating pattern having corresponding fold lines. In some embodiments, the pressing step 910 can include the step of heating the material 904 while being pressed, for example, by heating one or both of the mounting plates 902a and 902b. This heating may be effective to dry the material 904 within the mold. In the releasing step 920, the resulting cellulose-based material 906 can be substantially rigid with a desired undulating configuration. Alternatively, in some embodiments, the pressing step 910 can be carried out with sufficient pressure and / or duration to remove sufficient moisture such that the formable material 904 between the mounting plates 902a and 902b is converted into a rigid shaped structure without heating. Alternatively, in some embodiments, the pressing step 910 can be carried out without heating, and the material released from the mounting plates 902a and 902b in the releasing step 920 may be formable until it can then be dried. The equipment shown in FIG. 9 can be used to form an undulating pattern having fold lines in any direction with respect to the original longitudinal growth direction of the cellulose-based material.

[0069] Alternatively, to form the undulating pattern of FIG. 8, it is also possible to use a continuous manufacturing facility that employs roll processing. For example, a large wood sheet can be obtained by rotary cutting and then processed continuously through a first station for chemical treatment for partial delignification, a second station for drying, a third station for fluid impact treatment, and a fourth station for shaping. For example, FIG. 10A shows an exemplary manufacturing facility 1000 that employs continuous operation. The natural wood 1002 may be in the form of a log or a cylindrical rod, where the inner cavity extends in a direction perpendicular to the plane of the paper. The natural wood 1002 can be continuously cut, for example, by a rotary lathe 1004 and separated into thin continuous layers 1006 of natural wood for subsequent processing. The layer 1006 of natural wood can be conveyed to a station 1008 for the next step in the manufacturing process, such as by immersing the wood 1006 in a chemical solution 1010 to partially remove lignin from the wood, as described above with respect to process block 104 in method 100. In some embodiments, the size of station 1008 and the conveyance speed of the wood layer 1006 through station 1008 may correspond to the desired immersion time for the chemical treatment. Thus, the time from when a portion of layer 1006 enters the containment station 1008 until it exits towards the drying station 1012 corresponds to the immersion time for the desired amount of lignin removal.

[0070] After the delignification station 1008, the partially delignified wood may be conveyed to the drying station 1012. The drying station 1012 can apply any type of convective, conductive, or radiative heating to reduce the water content of the wood to 15 wt% or less, as described above with respect to process block 110 in method 100. For example, the drying station 1012 can employ forced air drying using air heated to a temperature of 80 °C or less for about 2 minutes. After the drying station 1012, the dried wood may be conveyed to the fluid impact station 1014. Here, the wood is immersed in a fluid 1016 (e.g., water, alcohol, or a combination thereof), as described above with respect to process block 112 in method 100. In particular, the fluid impact station 1014 can rehydrate the wood such that the moisture content of the wood passing therethrough is 35 wt%. Thereby, formable wood 1018 exiting station 1014 can be obtained.

[0071] After the fluid impact station 1014, the formable wood 1018 can be directed towards the forming station 1020. Here, as shown at 1026, the patterned rollers 1022 and 1024 have complementary shapes so as to press a desired undulating pattern onto the formable wood 1018. However, the facility shown in FIG. 10A can only be used to form a fold line that extends parallel to the original longitudinal growth direction of the wood. In some embodiments, the upper roller 1022 and the lower roller 1024 remain at a constant distance from each other at a distance smaller than the thickness of the formable wood 1018. Thereby, a pressing force is applied that further densifies the wood when forming the pattern. In some embodiments, during forming, one or both of the rollers 1022 and 1024 can be heated. Thereby, for example, the temperature of the wood 1018 can be made higher than room temperature during forming, and the wood can be transitioned from a flexible formable state to a rigid formed state. Alternatively or additionally, instead of heating the rollers 1022 and 1024, another heating mechanism may be provided to dry the formable wood 1018 at the forming station 1020 or a subsequent station, and the environment including the forming station 1020 or the subsequent environment may be heated.

[0072] Figure 10B shows another exemplary manufacturing facility 1050 that employs a continuous operation to form wood shaped using the undulating pattern of FIG. 8. The natural wood 1052 may be in the shape of a log or a cylindrical rod, where the inner cavity extends along direction 1054. The natural wood 1052 can be continuously cut, for example, by a rotating lathe 1056 and separated into thin, continuous veneer sheets 1058 of natural wood for subsequent processing. The veneer sheets 1058 can be conveyed, for example, to a delignification station 1060 where the veneer sheets 1058 are immersed in a chemical solution to partially remove lignin from the wood, as described above with respect to process block 104 in method 100. In some embodiments, the size of station 1060 and the conveyance speed of the veneer sheets 1058 may correspond to the desired immersion time for the chemical treatment. After the delignification station 1060, the partially delignified veneer sheets 1062 may be conveyed to a partial drying station 1064. The partial drying station 1064 can apply any type of convective, conductive, or radiative heating, for example, to reduce the water content of the wood to 35 wt%, as described above with respect to process block 108 in method 100. For example, the drying station 1064 can employ forced air drying using air heated to a temperature of 80° C. or less for about two minutes.

[0073] After the drying station 1064, the resulting formable wood can be directed to the forming station 1066. Here, as shown at 1072, the patterned rollers 1068 and 1070 have complementary shapes so as to press a desired undulating pattern onto the formable wood. However, the facility shown in FIG. 10B can only be used to form a fold line that extends parallel to the original longitudinal growth direction 1054 of the wood. In some embodiments, the upper roller 1068 and the lower roller 1070 remain a fixed distance from each other at a distance less than the thickness of the formable wood. Thereby, a pressing force is applied to further densify the wood when forming the pattern. In some embodiments, during forming, one or both of the rollers 1068 and 1070 can be heated. Thereby, for example, the temperature of the wood can be made higher than room temperature during forming, and the wood can be transitioned from a flexible formable state to a rigid formed state. Alternatively or additionally, the rollers 1068 and 1070 may not be heated, and another heating mechanism may be provided to dry the formable wood 1018 at the forming station 1020 or a subsequent station, and the environment including the forming station 1020 or the subsequent environment may be heated.

[0074] Note that it should be noted that the manufacturing facilities shown in FIGS. 9 to 10B can also be applied to the manufacture of formed cellulose-based materials having a shape configuration other than the undulating pattern of FIG. 8. However, the undulating pattern shown in the figure may be particularly useful when forming a structural material. In some embodiments, a plurality of formed cellulose-based materials having an undulating configuration can be assembled with one or more support plates to form a regularly arranged multilayer structure, a symmetrically arranged multilayer structure, a honeycomb composite, or any other support structure.

[0075] FIG. 11A shows a multilayer structure 1100 that employs a regular arrangement of a formed cellulose-based material, including, for example, a first formed fragment 1102 and a second formed fragment 1104. The first formed fragment 1102 is disposed between an upper support plate 1106 and an intermediate support plate 1108 and is optionally joined there (e.g., using epoxy, glue, or other adhesives), and the second formed fragment 1104 is disposed between a lower support plate 1110 and the intermediate support plate 1108 and can be optionally joined there (e.g., using epoxy, glue, or other adhesives). For example, each of the support plates 1106-1110 can be a metal plate (e.g., aluminum or an aluminum alloy) having a thickness of 1 mm, and each of the formed fragments 1102 and 1104 can have a thickness of 2 mm.

[0076] In the regular arrangement, the undulation patterns of the formed fragments 1102 and 1104 can be aligned in the thickness direction 1120 such that, for example, the valleys 1112 of the first fragment 1102 are aligned with the corresponding valleys 1116 of the second fragment 1104, and the peaks 1114 of the first fragment 1102 are aligned with the corresponding peaks 1118 of the second fragment 1104. In some embodiments, the cellulose-based material of the formed fragments 1102 and 1104 is arranged (e.g., perpendicular to the plane of the paper) such that the longitudinal growth direction is parallel to the folded portion of the undulation pattern. Alternatively, in some embodiments, the cellulose-based material of the formed fragments 1102 and 1104 is arranged (e.g., parallel to the plane of the paper) such that the longitudinal growth direction is perpendicular to the folded portion of the undulation pattern.

[0077] FIG. 11B shows another multilayer structure 1130 that employs a mirror-symmetric arrangement of a formed cellulose-based material, including, for example, a first formed fragment 1132 and a second formed fragment 1134. The first formed fragment 1132 is disposed between an upper support plate 1106 and an intermediate support plate 1108 and is optionally bonded there (e.g., using epoxy, glue, or other adhesives), and the second formed fragment 1134 is disposed between a lower support plate 1110 and the intermediate support plate 1108 and can be optionally bonded there (e.g., using epoxy, glue, or other adhesives). For example, each of the support plates 1106 - 1110 can be a metal plate (e.g., aluminum or an aluminum alloy) having a thickness of 1 mm, and each of the formed fragments 1132 and 1134 can have a thickness of 2 mm.

[0078] In the mirror-symmetric arrangement, the undulation patterns of the formed fragments 1132 and 1134 can be mirror-symmetric with respect to the intermediate support plate 1108. For example, the valleys 1142 of the first fragment 1132 are aligned with the corresponding peaks 1146 of the second fragment 1134, and the peaks 1144 of the first fragment 1132 are aligned with the corresponding valleys 1148 of the second fragment 1134. In some embodiments, the cellulose-based materials of the formed fragments 1132 and 1134 are arranged such that the longitudinal growth direction is parallel to the folded portion of the undulation pattern (e.g., perpendicular to the plane of the paper). Alternatively, in some embodiments, the cellulose-based materials of the formed fragments 1132 and 1134 are arranged such that the longitudinal growth direction is perpendicular to the folded portion of the undulation pattern (e.g., parallel to the plane of the paper).

[0079] In FIGS. 11A - 11B, the support plate is arranged parallel to the planes of the upper members of each peak region and the lower members of each valley - shaped region of the cellulose - based material (e.g., perpendicular to the plane of the paper). However, in some embodiments, the support plate is arranged perpendicular to the planes of the upper members of each peak region and the lower members of each valley - shaped region of the cellulose - based material (e.g., parallel to the plane of the paper). Further, in FIGS. 11A - 11B, the support plate is arranged between adjacent formed cellulose - based materials along the thickness direction. However, in some embodiments, adjacent formed cellulose - based materials can be directly bonded to each other without an intervening plate or member.

[0080] For example, FIGS. 12A - 12D show a configuration in which adjacent formed cellulose - based materials are directly bonded to each other to form a honeycomb (e.g., hexagonal pattern) core 1210, and support plates 1232 and 1234 are arranged perpendicular to the planes of the upper members of each peak region 1214 and the lower members of each valley - shaped region 1212 of the cellulose - based material 1200. For example, each formed cellulose - based material 1200 can be constructed using the continuous equipment of FIG. 10B. Since the size of the formed material generated by the continuous equipment may be larger than the desired thickness of the structural composite, the formed material 1200 can be cut into separate pieces at one or more cut surfaces 1202 and 1204. The longitudinal growth direction (and the extending direction of the longitudinal cells of the material) is parallel to the fold line using the continuous equipment of FIG. 10B and, for example, along direction 1206 in FIG. 12A. Alternatively, in some embodiments, for example, using the batch - processing equipment of FIG. 9, the cellulose - based material can be produced with the longitudinal growth direction perpendicular to the fold line and, for example, along direction 1208 in FIG. 12A.

[0081] In the composite structure 1230, the honeycomb core 1210 can be formed by arranging a plurality of shaped cellulose-based materials 1200 adjacent to each other in a mirror-symmetric arrangement as shown in FIG. 12B. The epoxy adhesives on the opposing surfaces 1222 and 1224 of the valleys 1212 and peaks 1214 can bond the adjacent materials 1200 together. When assembled, the honeycomb core 1210 can be disposed between an upper support plate 1232 and a lower support plate 1234 as shown in FIGS. 12C - 12D. The epoxy adhesives between the honeycomb core 1210 and the opposing surfaces of the support plates 1232 and 1234 can bond the support plates 1232 and 1234 to the core 1210. The resulting composite structure 1230 can have a load applied between the support plates 1232 - 1234 along direction 1206 so as to be parallel to the direction of extension of the cellulose fibers within each of the shaped cellulose-based materials 1200 forming the core 1210.

[0082] In some embodiments, one or both of the support plates 1232 - 1234 can be formed from a non-cellulose-based material such as a metal, metal alloy, ceramic, glass, composite, or polymer. For example, each support plate 1232 - 1234 can be a metal plate (e.g., aluminum or aluminum alloy) having a thickness of 1 mm, and the honeycomb core 1210 can have a thickness of 2 mm. Alternatively, in some embodiments, one or both support plates 1232 - 1234 can be formed from the same or a different cellulose-based material as the material forming the honeycomb core's shaping material. FIGS. 12A - 12C show a hexagonal shape formed by the undulating pattern of the assembled shaped materials, but the embodiments of the subject matter described herein are not limited thereto. Rather, the repeating shape within the honeycomb core can be made, for example, triangular, rectangular, rhombic, elliptical, or any other shape by appropriate adjustment of the undulating pattern.

[0083] [Manufacturing Examples and Experimental Results] [[First Example: Oak Wood]] In the first embodiment, oak wood was used as the raw material. After partial delignification, drying, and fluid impact, the formable oak wood was shaped to have a curved shape and then dried to form a rigid, shaped structure. The curved wood had high mechanical strength, low curvature, and low density. In particular, the obtained curved wood exhibited a high tensile strength of 345 MPa, which is three times that of conventional wood bent by running water pretreatment. On the other hand, the specific strength of the curved wood increased from 135 to 318 MPa·cm 3 / g.

[0084] [[Second Embodiment: Japanese Ash Wood]] In the second embodiment, Japanese ash wood was used to manufacture three-dimensional shaped wood. First, natural wood boards (Japanese ash wood, typical sample dimensions: 3.18 mm × 30 cm × 20 cm) were treated with a boiling aqueous solution of 2.5 M NaOH and 0.4 M Na2SO3 for 2 days and then immersed in water multiple times to remove the chemicals. Next, the partially delignified wood was air-dried at room temperature for 30 hours to form a dried wood intermediate. This was made formable by immersing it in water for 3 minutes (i.e., through the "fluid impact" process). Finally, the formable wood was shaped into the desired structure and air-dried at room temperature for 30 hours to remove moisture from the material, realizing three-dimensional shaped wood.

[0085] The three-dimensional shaped wood had improved mechanical properties for lightweight structural applications, such as a tensile strength of 300 MPa or less and a compressive strength of 60 MPa along the direction of the wood fibers. These are 6 times and 2 times higher, respectively, than those of natural raw wood. The improvement in the mechanical properties of the three-dimensional shaped wood is due to a high-density structure where the cell walls are intertwined densely at the microscale and the cellulose nanofibrils within the cell walls are well-aligned at the nanoscale. Also, the strength and specific stiffness of the three-dimensional shaped wood are even higher than those of Al-5052. With a low density of 0.75 g / cm 3 and being lightweight, the three-dimensional shaped wood has a specific strength of 386.8 MPa / (g / cm 3) had a high specific tensile strength. This is up to five times that of Al-5052 (84.4 MPa / (g / cm 3 ))). Furthermore, as shown in the Ashby plot of material stiffness versus density in Fig. 13A, the specific stiffness of three-dimensionally shaped wood exceeds that of hardwood, softwood, and polymers, suggesting its potential as a structural material.

[0086] [[Third Example: Composite Structure]] The low density, high mechanical strength, and excellent formability of three-dimensionally shaped wood bring wide versatility to large-scale designs, lightweight designs, load-bearing designs, and manufacturing of honeycomb structures that were conventionally made from metals such as polymers or Al-5052 alloys. The three-dimensionally shaped wood honeycomb structure was formed along the direction of the wood fibers. The three-dimensionally shaped wood honeycomb unit showed a specific compressive strength (51.6 MPa / (g / cm 3 )) equivalent to that of the Al-5052 honeycomb unit (46.8 MPa / (g / cm 3 )) as shown in Fig. 13B.

[0087] To evaluate the compression and bending properties of the assembled three-dimensionally shaped wood honeycomb core, a composite structure was fabricated with the core sandwiched between two aluminum plates. The composite structure showed a compressive strength of 9.1 MPa and a specific compressive strength of 91.0 MPa / (g / cm 3 ) (density 0.1 g / cm 3 basis), which is a higher value than that of the Al-5052 honeycomb structure. To further demonstrate the capabilities of this material, a composite structure was used to support the weight of a 1588 kg automobile. This corresponds to 1526 times the weight of the three-dimensionally shaped wood honeycomb core itself. To demonstrate scalability, an example of a three-dimensionally shaped wood honeycomb core with dimensions of 80 cm × 6 cm × 1.5 cm was fabricated.

[0088] When comparing the formed wood and the formable wood with other structural materials, the formed / formable wood was able to exhibit excellent mechanical properties. Regarding the load-bearing capacity, both the formed wood and the Al alloy honeycomb unit (e.g., height 1.5 cm, width 2 cm, length 4.4 cm, respective weights 1.3 g and 3.1 g, respective densities 0.10 g / cm 3 and 0.23 g / cm 3 ) were able to support 100 - 200 lbs without structural deformation or breakage. The paper honeycomb unit was easily broken by such weights. Also, the specific compressive strength was the highest for the formed wood honeycomb unit (51.6 MPa / (g / cm 3 )) which was much higher than that of the paper honeycomb unit (2.1 MPa / (g / cm 3 )) and also higher than that of the Al-5052 honeycomb unit (46.8 MPa / (g / cm 3 ). Regarding the foldability, the fold / unfold cycles before breakage or destruction of paper, Al-5052, and formable wood were 10 hours, 3 hours, and over 100 hours respectively. This confirmed the excellent flexibility of the formable wood material.

[0089] [[Fourth Embodiment: Cell Wall Structure]] Figure 14A is a schematic diagram showing the manufacturing process from natural wood to three-dimensional formed wood. To manufacture the three-dimensional formed wood, first, the natural wood was delignified to partially remove the brittle lignin component of the wood cell wall, and then it was completely air-dried over 30 hours. As shown in Figure 14B, due to drying, the cell wall shrank, closing the large and small channels (e.g., conduits and fibers respectively), and a shrunk wood intermediate was obtained. Then, the shrunk wood was immersed in water for a short time (e.g., 3 minutes) to give an "impact", and formable wood was obtained. The formable wood has a unique cell wall structure where "wrinkles" occur in the conduits and fibers during expansion, as shown in Figure 14C. By folding this formable wood, shaping it into any shape, and finally drying it for fixation, three-dimensional formed wood was obtained.

[0090] As a control material, natural wood was partially delignified by the same procedure and then air-dried without undergoing impact treatment with water to a moisture content of 50 wt%, which is the same as that of the formable wood. The obtained control material had a wrinkled cell wall structure without wrinkles and exhibited a fine structure of open cells similar to natural wood. However, since lignin was partially removed, it was confirmed that the cell walls were thinner and separated. This control material (referred to as non-formable wood) lacked flexibility and did not have wrinkles in the cell wall structure, even though it had the same moisture content as the formable wood, and thus broke when bent. Also, in the control experiments, it was found that all of dry natural wood (without spatial shrinkage, without water lubricant), wet natural wood (without spatial shrinkage), wet delignified wood (without spatial shrinkage), and shrunk wood (without water lubricant) had inferior folding ability due to the absence of spatial shrinkage and / or water lubricity.

[0091] To further investigate how the wrinkled cell wall structure enables the release of mechanical stress during folding and prevents material fracture, simulations were conducted. By fiber-scale mechanical modeling, it was shown that even when a nominal 60% strain deformation (tensile or compressive) was applied to the formable wood, the strain levels of all the cell walls in the formable wood were extremely low (maximum principal tensile strain 0.47%, compressive strain 2.66%). On the other hand, the maximum principal tensile strain in the cell walls of the non-formable wood was as high as 2.3% under the condition of a total elongation of 12.5%, which was significantly higher than that of the formable wood. Although both materials had undergone the delignification process, the non-formable wood fibers and conduits were open and only loosely in contact, while in the wrinkled cell walls of the formable wood that had undergone the drying / water impact process, the cell structure was more closed and in closer contact. As a result, the formable wood was characterized by sufficient hydrogen bonding between the cell walls and being resistant to peeling during folding, while the non-formable wood was easily destructible.

[0092] [[Example 5: Hole Formation]] The sinano wood was cut into a plurality of blocks 1500 each having a size of 5 cm in length × 5 cm in width × 5 mm in thickness. Each wood block 1500 was subjected to a chemical treatment 1502, specifically, immersed in a solution of NaOH (2.5 mol L -1 ) and Na2SQ3 (0.4 mol L -1 ) for 12 hours to partially remove lignin and hemicellulose. Then, in Comparative Example 1520 of FIG. 15A, the partially delignified wood block was subjected to hot pressing 1504, and then a 2-mm nail 1508 (or other elongated member with a sharp tip such as a needle) was pushed or inserted 1506 through the delignified block to form a hole 1510. However, in the resulting structure 1512, the cellulose fibers 1522 within the block may be broken at the edge 1514 of the nail hole 1510.

[0093] On the other hand, in Example 1540 of FIG. 15B, the partially delignified block is maintained in a formable state (e.g., by rehydration via drying and fluid impact, or by not drying it partially or completely, or by not drying the block before insertion of the nail 1546). Thus, a 2-mm nail 1546 can be inserted into the wet wood so that the cellulose fibers 1556 show sufficient mobility to bend around the edge of the hole 1550 without breaking. Then, the block was hot pressed for 24 hours to fix the diameter of the nail hole 1550. For the resulting structure 1552, the thickness of the wood was reduced to one-fifth of that of the natural wood block 1500, and the high-density wood could exhibit mechanical properties similar to those of the high-density wood after 1504 before formation of any gripping portion. However, the resulting structure 1552 can avoid breakage of the cellulose fibers at the edge of the hole 1550.

[0094] [Additional Examples of the Technology Described in this Specification] In view of the above-described implementation examples of the subject matter described in this specification, the present application describes additional embodiments in the following appendices. It should be noted that one feature of a single appendix, or a combination of two or more features of the appendices, and optionally, a combination with one or more features of one or more additional appendices, are also examples included in the disclosure of the present application.

[0095] [Appendix 1] (a) A step of producing a partially delignified wood fragment by subjecting a fragment of natural wood to one or more chemical treatments to remove at least a part of the lignin while maintaining the microstructure of the natural wood fragment, the microstructure including cellulose-based longitudinal cells extending along an extending direction substantially parallel to the longitudinal growth direction of the natural wood; (b) A step of drying the partially delignified wood fragment to remove moisture, whereby at least a part of the lumens of the cellulose-based longitudinal cells collapse and the moisture content of the dried fragment becomes 15 wt% or less; (c) A step of performing a fluid impact treatment on the dried fragment of the partially delignified wood to obtain a rehydrated fragment of the partially delignified wood, the fluid impact treatment including exposing the dried fragment to moisture, and the moisture content of the rehydrated fragment being at least 35 wt%; (d) A step of shaping the rehydrated fragment of the partially delignified wood from a substantially flat planar configuration into a non-planar three-dimensional configuration; comprising In the rehydrated fragment of the partially delignified wood, the lumen of the first cellulose-based longitudinal cell has a cross-sectional size smaller than the first size and is substantially collapsed, and the lumen of the second cellulose-based longitudinal cell in the rehydrated fragment of the partially delignified wood has a cross-sectional size larger than the first size and is at least partially open. Method.

[0096] [Appendix 2] The thickness of the fragment of natural wood in a direction perpendicular to the longitudinal direction is 10 mm or less (for example, 4 mm or less), the method described in any of the appendices or examples described in this specification, particularly the method described in Appendix 1.

[0097] [Appendix 3] (d) The moisture content of the rehydrated fragment during the step is at least 50 wt%, the method described in any of the appendices or examples described in this specification, particularly the method described in Appendix 1 or 2.

[0098] [Appendix 4] (a) A step of subjecting a fragment of natural wood to one or more chemical treatments to produce a partially delignified wood fragment by removing at least a part of the lignin while maintaining the microstructure of the natural wood fragment, wherein the microstructure includes cellulose-based longitudinal cells extending along an extending direction substantially parallel to the longitudinal growth direction of the natural wood; (b) A step of partially drying the partially delignified wood fragment to remove a part of the moisture, wherein the moisture content of the partially dried fragment of the partially delignified wood is at least 35%; (c) A step of shaping the partially dried fragment of the partially delignified wood from a substantially flat planar configuration to a non-planar three-dimensional configuration; comprising The lumen of the first cellulose-based longitudinal cell in the partially dried fragment of the partially delignified wood has a cross-sectional size smaller than the first size and is substantially collapsed, and the lumen of the second cellulose-based longitudinal cell in the partially dried fragment of the partially delignified wood has a cross-sectional size larger than the first size and is at least partially open. Method.

[0099] [Appendix 5] The thickness of the fragment of natural wood in a direction perpendicular to the longitudinal direction is in the range of 0.1 mm to 10 mm (including both ends) (for example, 0.5 mm or more and 10 mm or less), and is the method described in any of the appendices or examples described in this specification, particularly the method described in any one of Appendices 1 to 4.

[0100] [Appendix 6] The step of forming into a non-planar three-dimensional configuration includes the step of folding the fragment, or the step of bending the fragment, or any combination thereof, and is the method described in any of the appendices or examples described in this specification, particularly the method described in any one of Appendices 1 to 5.

[0101] [Appendix 7] After the step of forming into a non-planar three-dimensional configuration, (e) further includes the step of drying the fragment to remove moisture to set the shape of the fragment and form a rigid monolithic fragment of partially delignified wood having a non-planar three-dimensional configuration, The moisture content of the rigid monolithic fragment is 15 wt% or less, and is the method described in any of the appendices or examples described in this specification, particularly the method described in any one of Appendices 1 to 6.

[0102] [Appendix 8] Before the step of (e), further includes the step of forming at least one hole or opening extending in the thickness direction of the fragment of partially delignified wood having a moisture content of at least 35 wt%, The forming step includes using a non-machining method, and is the method described in any of the appendices or examples described in this specification, particularly the method described in Appendix 7.

[0103] [Appendix 9] After the step of (a) and before the step of (b), further includes the step of forming at least one hole or opening extending in the thickness direction of the fragment of partially delignified wood, The forming step includes using a non-machining method, The method described in any of the appendices or examples described in this specification, particularly the method described in any one of Appendices 1 to 8.

[0104] [Appendix 10] The step of forming at least one hole or opening includes pushing or inserting a needle, nail, or other elongated member with a sharp tip into the fragment, and is the method described in any of the appendices or examples described in this specification, particularly the method described in Appendix 9.

[0105] [Appendix 11] The drying (e) step includes exposing to an air or gas stream, exposing to a stagnant amount of air or gas, exposing to a vacuum, exposing to room temperature, heating to a temperature above room temperature, or any combination thereof, and is the method described in any of the appendices or examples described in this specification, particularly the method described in any one of Appendices 7 to 10.

[0106] [Appendix 12] The method further includes forming a protective layer or coating on a rigid monolithic fragment, and the protective layer or coating is configured to prevent rehydration of the rigid monolithic fragment, and is the method described in any of the appendices or examples described in this specification, particularly the method described in any one of Appendices 7 to 11.

[0107] [Appendix 13] Assembling a rigid monolithic fragment of partially delignified wood with one or more other rigid monolithic fragments of partially delignified wood, or Assembling a rigid monolithic fragment of partially delignified wood with one or more other fragments of wood, or Assembling a rigid monolithic fragment of partially delignified wood with one or more other fragments of non-wood materials (such as polymers, metals, metal alloys, cement, glass, ceramics, etc.) to form a composite structure, or further comprising any combination of these the method described in any of the appendices or examples described herein, particularly the method described in any one of Appendices 7 to 12.

[0108] [Appendix 14] The step of exposing to moisture (c) includes the step of partially or completely immersing in a fluid, or exposing to fluid vapor in a humid environment, or any combination of these, the method described in any of the appendices or examples described herein, particularly the method described in any one of Appendices 1 to 13.

[0109] [Appendix 15] The moisture content of the partially dried fragment during step (c) is at least 50 wt%, the method described in any of the appendices or examples described herein, particularly the method described in any one of Appendices 4 to 14.

[0110] [Appendix 16] Natural wood includes hardwood, the first cellulose-based longitudinal cells include fibers or tracheids of hardwood, and the second cellulose-based longitudinal cells include vessels of hardwood, the method described in any of the appendices or examples described herein, particularly the method described in any one of Appendices 1 to 15.

[0111] [Appendix 17] Natural wood includes softwood, and the first and second cellulose-based longitudinal cells include tracheids, the method described in any of the appendices or examples described herein, particularly the method described in any one of Appendices 1 to 15.

[0112] [Appendix 18] The lumen of each of the second cellulose-based longitudinal cells has a cross-sectional size after step (b) of drying that is smaller than the cross-sectional size of the natural wood before step (a), the method described in any of the appendices or examples described herein, particularly the method described in any one of Appendices 1 to 17.

[0113] [Appendix 19] The step (a) of performing one or more chemical treatments is carried out such that 0.1% to 99% (both ends included) of the lignin in natural wood is removed to produce fragments of partially delignified wood, or The step (a) of performing one or more chemical treatments is carried out such that 0.1% to 99% (both ends included) of the hemicellulose in natural wood is removed to produce fragments of partially delignified wood, or is any combination of these, the method described in any of the appendices or examples described herein, in particular the method described in any one of appendices 1 to 18.

[0114] [Appendix 20] The step (a) of performing one or more chemical treatments is carried out such that 50% or less of the lignin in natural wood is removed to produce fragments of partially delignified wood, or The step (a) of performing one or more chemical treatments is carried out such that 50% or less of the hemicellulose in natural wood is removed to produce fragments of partially delignified wood, or is any combination of these, the method described in any of the appendices or examples described herein, in particular the method described in any one of appendices 1 to 19.

[0115] [Appendix 21] The step (a) of performing one or more chemical treatments is carried out such that the lignin content in natural wood is reduced by 10% or less to produce fragments of partially delignified wood, or The step (a) of performing one or more chemical treatments is carried out such that the hemicellulose content in natural wood is reduced by 10% or less to produce fragments of partially delignified wood, or is any combination of these, the method described in any of the appendices or examples described herein, in particular the method described in any one of appendices 1 to 20.

[0116] [Appendix 22] The natural wood is hardwood, and the lignin content of the partially delignified wood fragments after step (a) is at least 10 wt%, or The natural wood is softwood, and the lignin content of the partially delignified wood fragments after step (a) is at least 12.5 wt%. The method described in any of the appendices or examples described herein, particularly the method described in any one of appendices 1 to 21.

[0117] [Appendix 23] The method described in any of the appendices or examples described herein, particularly the method described in any one of appendices 1 to 22, wherein at least one of the one or more chemical treatments includes partial or total immersion in one or more chemical solutions.

[0118] [Appendix 24] The method described in any of the appendices or examples described herein, particularly the method described in appendix 23, wherein the one or more chemical solutions include an alkaline solution.

[0119] [Appendix 25] The one or more chemical solutions are sodium hydroxide (NaOH), lithium hydroxide (LiOH), potassium hydroxide (KOH), sodium sulfite (Na2SO3), sodium sulfate (Na2SO4), sodium sulfide (Na2S), Na n S (where n is an integer), urea (CH4N2O), sodium bisulfite (NaHSO3), sulfur dioxide (SO2), anthraquinone (C 14H8O2), methanol (CH3OH), ethanol (C2H5OH), butanol (C4H9OH), formic acid (CH2O2), hydrogen peroxide (H2O2), acetic acid (CH3COOH), butyric acid (C4H8O2), performic acid (CH2O3), peracetic acid (C2H4O3), ammonia (NH3), p-toluenesulfonic acid (p-TsOH), sodium hypochlorite (NaClO), sodium chlorite (NaClO2), chlorine dioxide (ClO2), chlorine (Cl2), or any combination thereof, the method described in any of the appendices or examples described herein, particularly the method described in appendix 23 or 24.

[0120] [Appendix 26] One or more chemical solutions include a boiling solution of NaOH and Na2SO3, the method described in any of the appendices or examples described herein, particularly the method described in any one of appendices 23 to 25.

[0121] [Appendix 27] Before step (a), further comprising the step of cutting a substantially cylindrical portion of natural wood using rotary cutting technology to form a fragment of natural wood as a veneer, the method described in any of the appendices or examples described herein, particularly described in any one of appendices 1 to 26.

[0122] [Appendix 28] A formable wood structure formed by the method described in any of the appendices or examples described herein, particularly the method described in any one of appendices 1 to 27.

[0123] [Appendix 29] A rigid formed wood structure formed by the method described in any of the appendices or examples described herein, particularly the method described in any one of appendices 1 to 27.

[0124] [Appendix 30] A structural material, At least two dried monolithic fragments of partially delignified wood, each of the dried monolithic fragments being formed to have a repeating undulating configuration formed by being folded or bent multiple times, the undulating configuration having a repeating pattern including at least one peak and at least one valley, and the moisture content of each of the dried monolithic fragments being 15 wt% or less, and at least two dried monolithic fragments, a first support plate and a second support plate coupled to the at least two dried monolithic fragments, A structural material comprising.

[0125] [Appendix 31] The folding or bending in the undulating configuration is performed about respective axes parallel to the first direction, the support plates are disposed on both sides of the dried monolithic fragment with respect to the first direction so as to sandwich the monolithic fragment, and the structural material is a structural material having a honeycomb configuration, a structural material described in any of the appendices or examples described herein, particularly the structural material described in Appendix 30.

[0126] [Appendix 32] The opposing surfaces of adjacent ones of the at least two dried monolithic fragments are joined to each other, a structural material described in any of the appendices or examples described herein, particularly the structural material described in Appendix 30 or 31.

[0127] [Appendix 33] Each of the dried monolithic fragments has a density of less than 1.5 g / cm 3 (e.g., 1 g / cm or less 3 ), a tensile strength of at least 140 MPa (e.g., 200 MPa or more), a compressive strength of at least 40 MPa, a specific tensile strength of at least 115 MPa / (g / cm 3 )(e.g., 300 MPa / (g / cm 3 ) or more), or any combination thereof, a structural material described in any of the appendices or examples described herein, particularly the structural material described in any one of Appendices 30 to 32.

[0128] [Appendix 34] The structural material has a compressive strength of at least 3 MPa (for example, 5 MPa or more), a specific compressive strength of at least 30 MPa / (g / cm 3 )(for example, 50 MPa / (g / cm 3 ) or more), or any combination thereof, and is the structural material described in any of the appendices or examples described herein, particularly the structural material described in any one of Appendices 30 to 33.

[0129] [Appendix 35] Each of the dried monolithic fragments has a plurality of peaks and a plurality of valleys, and is the structural material described in any of the appendices or examples described herein, particularly the structural material described in any one of Appendices 30 to 34.

[0130] [Appendix 36] Each of the dried monolithic fragments is in contact with both the first support plate and the second support plate, and is the structural material described in any of the appendices or examples described herein, particularly the structural material described in any one of Appendices 30 to 35.

[0131] [Appendix 37] One or both of the support plates include another dried fragment of partially delignified natural wood having a substantially flat planar configuration, and is the structural material described in any of the appendices or examples described herein, particularly the structural material described in any one of Appendices 30 to 36.

[0132] [Appendix 38] One or both of the first support plate and the second support plate are formed from one or more non-wood materials (for example, polymers, metals, metal alloys, cement, glass, ceramics, composites, or any combination thereof), and are the structural material described in any of the appendices or examples described herein, particularly the structural material described in any one of Appendices 30 to 37.

[0133] [Appendix 39] The structural material described in any of the appendices or examples described herein, particularly the structural material described in any one of Appendices 30 to 38, which is sealed to prevent the ingress of moisture into at least two dry monolithic fragments.

[0134] [Appendix 40] Further comprising a protective layer or coating formed on the outer surfaces of at least two dry monolithic fragments, At least two dry monolithic fragments are sealed against the ingress of moisture by the protective layer or coating. The structural material described in any of the appendices or examples described herein, particularly the structural material described in any one of Appendices 30 to 39.

[0135] [Appendix 41] Further comprising a third support plate, Folding or bending in a corrugated configuration is performed about respective axes parallel to the first direction, The first support plate and the second support plate are disposed on both sides of the first dry monolithic fragment with respect to a second direction substantially perpendicular to the first direction, The second support plate and the third support plate are disposed on both sides of the second dry monolithic fragment with respect to the second direction. The structural material described in any of the appendices or examples described herein, particularly the structural material described in any one of Appendices 30 to 40.

[0136] [Appendix 42] In a side view, the peak portions of the corrugated configuration of the first dry monolithic fragment are substantially aligned with the corresponding peak portions of the corrugated configuration of the second dry monolithic fragment, the structural material described in any of the appendices or examples described herein, particularly the structural material described in any one of Appendices 30 to 41.

[0137] [Appendix 43] In a side view, the peak portions of the undulating configuration of the first dried monolithic fragment are substantially aligned with the corresponding valley-shaped portions of the undulating configuration of the second dried monolithic fragment. The structural material described in any of the appendices or examples described herein, particularly the structural material described in any one of Appendices 30 to 41.

[0138] [Appendix 44] In the respective microstructures of the dried monolithic fragments of partially delignified wood, the cellulose-based longitudinal cells of the wood are substantially collapsed, and each of the longitudinal cells extends along an extending direction substantially parallel to the longitudinal growth direction of natural wood. The structural material described in any of the appendices or examples described herein, particularly the structural material described in any one of Appendices 30 to 43.

[0139] [Appendix 45] The cellulose nanofibers forming the walls of the collapsed longitudinal cells of each of the monolithic fragments of partially delignified wood extend substantially parallel to the extending direction. The structural material described in any of the appendices or examples described herein, particularly the structural material described in any one of Appendices 30 to 44.

[0140] [Appendix 46] The wood for at least two dried monolithic fragments includes hardwood or softwood. The structural material described in any of the appendices or examples described herein, particularly the structural material described in any one of Appendices 30 to 45.

[0141] [Appendix 47] Each of at least two dried monolithic fragments of partially delignified wood is produced by reducing the lignin content of each fragment of natural wood by 0.1% to 99% (including both ends), or Each of at least two dried monolithic fragments of partially delignified wood is produced by reducing the hemicellulose content of each fragment of natural wood by 0.1% to 99% (including both ends), or Any combination of these. The structural materials described in any of the appendices or examples described in this specification, particularly the structural materials described in any one of Appendices 30 to 46.

[0142] [Appendix 48] Each of at least two dried monolithic fragments of partially delignified wood is produced by reducing the lignin content of each fragment of natural wood by 50% or less, or Each of at least two dried monolithic fragments of partially delignified wood is produced by reducing the hemicellulose content of each fragment of natural wood by 50% or less, or is any combination of these. The structural materials described in any of the appendices or examples described in this specification, particularly the structural materials described in any one of Appendices 30 to 47.

[0143] [Appendix 49] Each of at least two dried monolithic fragments of partially delignified wood is produced by reducing the lignin content of each fragment of natural wood by 10% or less, or Each of at least two dried monolithic fragments of partially delignified wood is produced by reducing the hemicellulose content of each fragment of natural wood by 10% or less, or is any combination of these. The structural materials described in any of the appendices or examples described in this specification, particularly the structural materials described in any one of Appendices 30 to 48.

[0144] [Appendix 50] The amount of lignin in each dried monolithic fragment of partially delignified wood is at least 10 wt%, the structural materials described in any of the appendices or examples described in this specification, particularly the structural materials described in any one of Appendices 30 to 49.

[0145] [Appendix 51] A formable wood structure, comprising a monolithic fragment of partially delignified natural wood having a moisture content of at least 35 wt%, the monolithic fragment has a microstructure, the lumen of the first cellulose-based longitudinal cells of the natural wood has a cross-sectional size smaller than the first size and is substantially collapsed, and the lumen of the second cellulose-based longitudinal cells of the natural wood has a cross-sectional size larger than the first size and is at least partially open, the cellulose-based longitudinal cells extend along an extending direction substantially parallel to the longitudinal growth direction of the natural wood, a formable wood structure.

[0146] [Appendix 52] The moisture content is at least 50 wt%, the wood structure described in any of the appendices or examples described herein, particularly the wood structure described in Appendix 51.

[0147] [Appendix 53] For each lumen of the second cellulose-based longitudinal cells, the cross-sectional size in the monolithic fragment is smaller than the cross-sectional size in the natural wood before partial delignification, the wood structure described in any of the appendices or examples described herein, particularly the wood structure described in any one of Appendices 51 to 52.

[0148] [Appendix 54] The monolithic fragment is constructed to elastically deform by being bent or folded within an angular range of 0 ° ~180 ° (including both ends), the wood structure described in any of the appendices or examples described herein, particularly the wood structure described in any one of Appendices 51 to 53.

[0149] [Appendix 55] The monolithic fragment is elastically deformable without fatigue in at least 100 folding cycles, the wood structure described in any of the appendices or examples described herein, particularly the wood structure described in any one of Appendices 51 to 54.

[0150] [Appendix 56] A formed wood structure, Including the formable wood structure according to claim 51, which is formed into a non-planar three-dimensional configuration and then dried to remove moisture, and has a moisture content of 15 wt% or less. The wood structure described in any of the appendices or examples described herein, particularly the wood structure described in any one of appendices 51 to 55.

[0151] [Appendix 57] The non-planar three-dimensional configuration includes, for a monolithic fragment, a origami-folded shape or a cut-paper-folded shape, the wood structure described in any of the appendices or examples described herein, particularly the wood structure described in appendix 56.

[0152] [Appendix 58] A formed wood structure, Including a dried monolithic fragment of partially delignified natural wood formed into a non-planar three-dimensional configuration, and the moisture content of the dried monolithic fragment is 15 wt% or less. The microstructure of the dried monolithic fragment has the lumen of the cellulose-based longitudinal cells of the wood, the lumen is substantially collapsed, and each of the longitudinal cells extends along an extending direction substantially parallel to the longitudinal growth direction of the natural wood. The formed wood structure.

[0153] [Appendix 59] The non-planar three-dimensional configuration includes at least two bent or folded portions in the monolithic fragment, the wood structure described in any of the appendices or examples described herein, particularly the wood structure described in any one of appendices 56 to 58.

[0154] [Appendix 60] The thickness of the monolithic fragment at at least two bent or folded portions is substantially the same as the thickness of the unbent or unfolded portion of the monolithic fragment, the wood structure described in any of the appendices or examples described herein, particularly the wood structure described in appendix 59.

[0155] [Appendix 61] At least one of the bent or folded portions is bent or folded about an axis substantially parallel to the extending direction, the wood structure described in any of the appendices or examples described herein, in particular the wood structure described in any one of Appendices 59 to 60.

[0156] [Appendix 62] At least one of the bent or folded portions forms an interior angle of less than 180 ° , the wood structure described in any of the appendices or examples described herein, in particular the wood structure described in any one of Appendices 59 to 61.

[0157] [Appendix 63] At least one of the bent or folded portions forms an interior angle of 135 or less ° , the wood structure described in any of the appendices or examples described herein, in particular the wood structure described in any one of Appendices 59 to 62.

[0158] [Appendix 64] At least one of the bent or folded portions is bent or folded about an axis intersecting the extending direction, or At least one of the bent or folded portions is bent or folded about an axis parallel to the extending direction, or is any combination of these , the wood structure described in any of the appendices or examples described herein, in particular the wood structure described in any one of Appendices 59 to 63.

[0159] [Appendix 65] The dried monolithic fragment is constructed to plastically deform by being folded or bent, the wood structure described in any of the appendices or examples described herein, in particular the wood structure described in any one of Appendices 56 to 64.

[0160] [Supplementary Note 66] Further comprising a protective layer or coating formed on the outer surface of the dried monolithic fragment, the protective layer or coating preventing the ingress of moisture into the monolithic fragment, a wood structure as described in any of the supplementary notes or examples described herein, in particular a wood structure as described in any one of supplementary notes 51 to 65.

[0161] [Supplementary Note 67] Natural wood includes hardwood or softwood, a wood structure as described in any of the supplementary notes or examples described herein, in particular a wood structure as described in any one of supplementary notes 51 to 66.

[0162] [Supplementary Note 68] Natural wood includes hardwood, the first cellulose-based longitudinal cells include fibers or tracheids of hardwood, and the second cellulose-based longitudinal cells include vessels of hardwood, a wood structure as described in any of the supplementary notes or examples described herein, in particular a wood structure as described in any one of supplementary notes 51 to 67.

[0163] [Supplementary Note 69] Natural wood includes softwood, and the first cellulose-based longitudinal cells and the second cellulose-based longitudinal cells include tracheids, a wood structure as described in any of the supplementary notes or examples described herein, in particular a wood structure as described in any one of supplementary notes 51 to 67.

[0164] [Supplementary Note 70] The monolithic fragment is produced by reducing the lignin content of natural wood by 0.1% to 99%, or The monolithic fragment is produced by reducing the lignin content of natural wood by 0.1% to 99%, or is any combination of these, a wood structure as described in any of the supplementary notes or examples described herein, in particular a wood structure as described in any one of supplementary notes 51 to 69.

[0165] [Supplementary Note 71] The monolithic fragment is produced by reducing the lignin content of natural wood to 50% or less, or The monolithic fragment is produced by reducing the lignin content of natural wood to 50% or less, or is any combination of these, a wood structure described in any of the appendices or examples described herein, particularly a wood structure described in any one of appendices 51 to 70.

[0166] [Appendix 72] The monolithic fragment is produced by reducing the lignin content of natural wood to 10% or less, or The monolithic fragment is produced by reducing the lignin content of natural wood to 10% or less, or is any combination of these, a wood structure described in any of the appendices or examples described herein, particularly a wood structure described in any one of appendices 51 to 71.

[0167] [Appendix 73] The amount of lignin in the monolithic fragment is at least 10 wt%, a wood structure described in any of the appendices or examples described herein, particularly a wood structure described in any one of appendices 51 to 72.

[0168] [Appendix 74] The thickness of the monolithic fragment is at least 0.1 mm (for example, 0.5 mm or more), or The thickness of the monolithic fragment is 10 mm or less, or The thickness of the monolithic fragment is 0.1 mm to 10 mm (including both ends) (for example, 0.5 mm or more and 10 mm or less), a wood structure described in any of the appendices or examples described herein, particularly a wood structure described in any one of appendices 51 to 73.

[0169] [Appendix 75] The thickness of the monolithic fragment is along a direction substantially perpendicular to the extending direction, a wood structure described in any of the appendices or examples described herein, particularly a wood structure described in Appendix 74.

[0170] [Appendix 76] The monolithic fragment has a first dimension and a second dimension in a plane perpendicular to the thickness direction, the first dimension and the second dimension are orthogonal to each other, and at least one of the first dimension and the second dimension is at least 10 times greater than the thickness. The wood structure described in any of the appendices or examples described herein, particularly the wood structure described in any one of Appendices 74 to 75.

[0171] [Appendix 77] The cellulose nanofibers forming the longitudinal cell walls of the monolithic fragment extend substantially parallel to the extending direction. The wood structure described in any of the appendices or examples described herein, particularly the wood structure described in any one of Appendices 51 to 76.

[0172] [Appendix 78] (a) A step of producing a partially delignified cellulose-based material fragment by subjecting a fragment of a naturally occurring cellulose-based material to one or more chemical treatments to remove at least a part of the lignin while maintaining the fine structure of the fragment of the naturally occurring cellulose-based material. The fine structure includes cellulose-based longitudinal cells extending along an extending direction substantially parallel to the longitudinal growth direction of the naturally occurring cellulose-based material. (b) A step of drying the partially delignified cellulose-based material fragment to remove moisture, whereby at least a part of the lumen of the cellulose-based longitudinal cells collapses and the moisture content of the dried fragment becomes 15 wt% or less. (c) A step of performing a fluid impact treatment on the dried fragment of the partially delignified cellulose-based material to obtain a rehydrated fragment of the partially delignified cellulose-based material. The fluid impact treatment includes exposing the dried fragment to moisture, and the moisture content of the rehydrated fragment is at least 35 wt%. (d) A step of shaping the rehydrated fragment of the partially delignified cellulose-based material from a substantially flat planar configuration to a non-planar three-dimensional configuration. including The lumen of the first cellulosic longitudinal cell in the rehydrated fragment of the partially delignified cellulosic material has a cross-sectional size smaller than the first size, is substantially collapsed, and the lumen of the second cellulosic longitudinal cell in the rehydrated fragment of the partially delignified cellulosic material has a cross-sectional size larger than the first size and is at least partially open. Method.

[0173] [Appendix 79] The water content of the rehydrated fragment during the step of (d) is at least 50 wt%, the method according to any of the appendices or examples described herein, in particular the method described in Appendix 78.

[0174] [Appendix 80] (a) A step of producing a fragment of a partially delignified cellulosic material by subjecting a fragment of a naturally occurring cellulosic material to one or more chemical treatments to remove at least a part of the lignin while maintaining the microstructure of the fragment of the naturally occurring cellulosic material, wherein the microstructure includes cellulosic longitudinal cells extending along an extending direction substantially parallel to the longitudinal growth direction of the naturally occurring cellulosic material. (b) A step of partially drying the fragment of the partially delignified cellulosic material to remove a part of the water, wherein the water content of the partially dried fragment of the partially delignified cellulosic material is at least 35%. (c) A step of shaping the partially dried fragment of the partially delignified cellulosic material from a substantially flat planar configuration to a non-planar three-dimensional configuration. comprising The lumen of the first cellulosic longitudinal cell in the partially dried fragment of the partially delignified cellulosic material has a cross-sectional size smaller than the first size, is substantially collapsed, and the lumen of the second cellulosic longitudinal cell in the partially dried fragment of the partially delignified cellulosic material has a cross-sectional size larger than the first size and is at least partially open. Method.

[0175] [Appendix 81] After the step of forming into a non-planar three-dimensional configuration, (e) further comprising the step of drying the fragment to remove moisture, setting the shape of the fragment, and forming a rigid monolithic fragment of the partially delignified cellulose-based material having a non-planar three-dimensional configuration, The moisture content of the rigid monolithic fragment is 15 wt% or less. The method described in any of the appendices or examples described herein, particularly the method described in any one of Appendices 78 to 80.

[0176] [Appendix 82] The naturally occurring cellulose-based material is a fibrous plant, the method described in any of the appendices or examples described herein, particularly the method described in any one of Appendices 78 to 81.

[0177] [Appendix 83] The fibrous plant is hardwood, softwood, bamboo, grass, or reed, the method described in any of the appendices or examples described herein, particularly the method described in Appendix 82.

[0178] [Appendix 84] The step (a) of performing one or more chemical treatments is carried out such that the lignin content of the naturally occurring cellulose-based material is reduced by 0.1% to 99% (both ends included) to produce a fragment of the partially delignified cellulose-based material, or The step (a) of performing one or more chemical treatments is carried out such that the hemicellulose content of the naturally occurring cellulose-based material is reduced by 0.1% to 99% (both ends included) to produce a fragment of the partially delignified cellulose-based material, or is any combination of these. The method described in any of the appendices or examples described herein, particularly the method described in any one of Appendices 78 to 83.

[0179] [Appendix 85] The step (a) of subjecting the one or more chemical treatments is carried out such that the lignin content of the naturally occurring cellulosic material is reduced by 50% or less to produce fragments of a partially delignified cellulosic material, or The step (a) of subjecting the one or more chemical treatments is carried out such that the hemicellulose content of the naturally occurring cellulosic material is reduced by 50% or less to produce fragments of a partially delignified cellulosic material, or is any combination of these, The method described in any of the appendices or examples described herein, particularly the method described in any one of appendices 78 to 84.

[0180] [Appendix 86] The step (a) of subjecting the one or more chemical treatments is carried out such that the lignin content of the naturally occurring cellulosic material is reduced by 10% or less to produce fragments of a partially delignified cellulosic material, or The step (a) of subjecting the one or more chemical treatments is carried out such that the hemicellulose content of the naturally occurring cellulosic material is reduced by 10% or less to produce fragments of a partially delignified cellulosic material, or is any combination of these, The method described in any of the appendices or examples described herein, particularly the method described in any one of appendices 78 to 85.

[0181] [Appendix 87] The naturally occurring cellulosic material is hardwood, and the amount of lignin in the fragments of the partially delignified wood after step (a) is at least 10 wt%, or The naturally occurring cellulosic material is softwood, and the amount of lignin in the fragments of the partially delignified wood after step (a) is at least 12.5 wt%, or The naturally occurring cellulosic material is bamboo, and the amount of lignin in the fragments of the partially delignified bamboo after step (a) is at least 13 wt%. The method described in any of the appendices or examples described in this specification, particularly the method described in any one of Appendices 78 to 86.

[0182] [Appendix 88] A formable structure formed by the method described in any of the appendices or examples described in this specification, particularly the method described in any one of Appendices 78 to 87.

[0183] [Appendix 89] A rigid formed structure formed by the method described in any of the appendices or examples described in this specification, particularly the method described in any one of Appendices 78 to 87.

[0184] [Appendix 90] A structural material comprising: At least two dried monolithic fragments of a partially delignified cellulosic material, each of the dried monolithic fragments being formed to have a repeating undulating configuration formed by being folded or bent multiple times, the undulating configuration having a repeating pattern including at least one peak and at least one valley, and the moisture content of each of the dried monolithic fragments being 15 wt% or less; at least two dried monolithic fragments; A first support plate and a second support plate bonded to the at least two dried monolithic fragments; And a structural material comprising the same.

[0185] [Appendix 91] The folding or bending in the undulating configuration is performed about respective axes parallel to a first direction, the support plates are disposed on both sides of the dried monolithic fragment with respect to the first direction so as to sandwich the monolithic fragment, and the structural material has a honeycomb configuration. The structural material described in any of the appendices or examples described in this specification, particularly the structural material described in Appendix 90.

[0186] [Appendix 92] A formable structure comprising: Containing a monolithic fragment of a partially delignified, naturally occurring cellulosic material with a moisture content of at least 35 wt%, The monolithic fragment has a microstructure, the lumen of the first cellulosic longitudinal cell of the naturally occurring cellulosic material has a cross-sectional size smaller than the first size and is substantially collapsed, and the lumen of the second cellulosic longitudinal cell of the naturally occurring cellulosic material has a cross-sectional size larger than the first size and is at least partially open, The cellulosic longitudinal cells extend along an extension direction substantially parallel to the longitudinal growth direction of the naturally occurring cellulosic material. A formable structure.

[0187] [Appendix 93] The moisture content is at least 50 wt%, the structure described in any of the appendices or examples described herein, particularly the structure described in Appendix 92.

[0188] [Appendix 94] A formed structure, formed into a non-planar three-dimensional configuration and then dried to remove moisture, the formable structure described in any of the appendices or examples described herein with a moisture content of 15 wt% or less, particularly the formable structure described in any one of Appendices 92 to 93.

[0189] [Appendix 95] A formed structure, Containing a dried monolithic fragment of a partially delignified, naturally occurring cellulosic material formed into a non-planar three-dimensional configuration, the moisture content of the dried monolithic fragment is 15 wt% or less, The microstructure of the dried monolithic fragment has the lumen of the cellulosic longitudinal cells of the cellulosic material, the lumen is substantially collapsed, and each of the longitudinal cells extends along an extension direction substantially parallel to the longitudinal growth direction of the naturally occurring cellulosic material. A formed structure.

[0190] [Appendix 96] Naturally occurring cellulosic materials are fibrous plants, the structures described in any of the appendices or examples described herein, particularly the structures described in any one of appendices 90 to 95.

[0191] [Appendix 97] Fibrous plants are hardwoods, softwoods, bamboo, grass, or reeds, the structures described in any of the appendices or examples described herein, particularly the structures described in appendix 96.

[0192] [Conclusion] The above features illustrated or described with respect to FIGS. 1 to 15B and appendices 1 to 97 can all be combined with other features illustrated or described with respect to FIGS. 1 to 15B and appendices 1 to 97, and materials, structures, methods, devices, and embodiments not illustrated or specifically described herein can be provided. For example, the features regarding the formation of wet holes described with respect to FIG. 15B can be applied to other materials described herein, such as the structures and methods described with respect to FIGS. 4A to 12D. Also, according to one or more contemplated embodiments, other combinations and variations are possible. All of the features described herein are independent of each other and can be used in combination with other features described herein, except where structurally impossible.

[0193] It should be noted that in view of the many possible embodiments to which the principles of the technology described herein can be applied, the illustrated embodiments are merely preferred examples of the technology described herein and do not limit the technology described herein. Rather, the scope of the technology described herein is defined by the appended claims. Accordingly, the applicant can claim that all that is within the scope and spirit of these claims is the invention.

Claims

Claim 1 (a) A step of subjecting a fragment of a naturally occurring cellulosic material to one or more chemical treatments to produce a fragment of a partially delignified cellulosic material by removing at least a part of lignin while maintaining the fine structure of the fragment of the naturally occurring cellulosic material, wherein the fine structure includes cellulosic longitudinal cells extending along an extending direction substantially parallel to the longitudinal growth direction of the naturally occurring cellulosic material; (b) After the step (a), a step of partially drying the fragment of the partially delignified cellulosic material to remove a part of moisture, wherein the partially delignified cellulosic material has a moisture content of at least 35 wt% when partially dried, the lumen of the first cellulosic longitudinal cell in the partially delignified cellulosic material has a cross-sectional size smaller than a first size and is substantially collapsed, and the lumen of the second cellulosic longitudinal cell in the partially delignified cellulosic material has a cross-sectional size larger than the first size and is at least partially open; (c) After the step (b), a step of shaping the fragment of the partially delignified cellulosic material from a substantially flat planar configuration into a non-planar three-dimensional configuration; (d) A step of further drying the fragment of the partially delignified cellulosic material to remove additional moisture, wherein the fragment of the partially delignified cellulosic material has a moisture content of 15 wt% or less when further dried, thereby setting the shape of the fragment to the non-planar three-dimensional configuration and forming a rigid monolithic fragment of the partially delignified cellulosic material. comprising a method. Claim 2 The method according to claim 1, wherein the thickness of the fragment of the naturally occurring cellulosic material in a direction perpendicular to the extending direction is in the range of 0.1 mm to 10 mm (including both ends). Claim 3 The method according to claim 1, wherein the step of shaping into the non-planar three-dimensional configuration includes a step of folding the fragment, or a step of bending the fragment, or any combination thereof. Claim 4 The method according to claim 1, further comprising the step of forming a protective layer or coating on the rigid monolithic fragment, wherein the protective layer or coating is configured to prevent rehydration of the rigid monolithic fragment.

5. The method according to claim 1, wherein the moisture content of the fragment of the partially delignified cellulosic material during step (c) is at least 50 wt%.

6. The method according to claim 1, wherein the naturally occurring cellulosic material is hardwood, softwood, bamboo, grass, or reed.

7. The naturally occurring cellulosic material includes hardwood, the first cellulosic longitudinal cells include fibers or tracheids of the hardwood, the second cellulosic longitudinal cells include vessels of the hardwood, or The naturally occurring cellulosic material includes softwood, and the first and second cellulosic longitudinal cells include tracheids.

8. The cross-sectional size of each lumen of the second cellulosic longitudinal cells after the partial drying of step (b) and before the shaping of step (c) is smaller than the cross-sectional size in the naturally occurring cellulosic material before step (a).

9. The step (a) of performing the one or more chemical treatments is carried out such that the lignin content of the naturally occurring cellulosic material is reduced by 0.1% to 99% (both ends included) to produce a fragment of the partially delignified cellulosic material, or The step (a) of performing the one or more chemical treatments is carried out such that the hemicellulose content of the naturally occurring cellulosic material is reduced by 0.1% to 99% (both ends included) to produce a fragment of the partially delignified cellulosic material, or any combination thereof. The method according to claim 1.

10. The naturally occurring cellulosic material is hardwood, and the amount of lignin in the fragment of the partially delignified cellulosic material after step (a) is at least 10 wt%, or The naturally occurring cellulosic material is softwood, and the amount of lignin in the fragment of the partially delignified cellulosic material after step (a) is at least 12.5 wt%, or The naturally occurring cellulosic material is bamboo, and the amount of lignin in the partially delignified bamboo fragments after the step (a) is at least 13 wt%. The method according to claim 1. **Claim 11** The further drying in step (d) includes the step of exposing the fragments of the partially delignified cellulosic material to an air or gas stream, the step of exposing the fragments of the partially delignified cellulosic material to a stagnant amount of air or gas, the step of exposing the fragments of the partially delignified cellulosic material to room temperature, the step of heating the fragments of the partially delignified cellulosic material to a temperature above room temperature, or any combination thereof. The method according to claim 1. **Claim 12** After the step (d), assembling the rigid monolithic fragment of the partially delignified cellulosic material with one or more other rigid monolithic fragments of the partially delignified cellulosic material, or assembling the rigid monolithic fragment of the partially delignified cellulosic material with one or more other fragments of the cellulosic material, or assembling the rigid monolithic fragment of the partially delignified cellulosic material with one or more other fragments of a non-cellulosic material to form a composite structure, or any combination thereof is further included. The method according to claim 1. **Claim 13**: The one or more chemical treatments include treatment with sodium hydroxide (NaOH), lithium hydroxide (LiOH), potassium hydroxide (KOH), sodium sulfite (Na₂SO₃), sodium sulfate (Na₂SO₄), sodium sulfide (Na₂S), NanS (where n is an integer), urea (CH₄N₂O), sodium bisulfite (NaHSO₃), sulfur dioxide (SO₂), anthraquinone (C₁₄H₈O₂), methanol (CH₃OH), ethanol (C₂H₅OH), butanol (C₄H₉OH), formic acid (CH₂O₂), hydrogen peroxide (H₂O₂), acetic acid (CH₃COOH), butyric acid (C₄H₈O₂), performic acid (CH₂O₃), peracetic acid (C₂H₄O₃), ammonia (NH₃), p-toluenesulfonic acid (p-TsOH), sodium hypochlorite (NaClO), sodium chlorite (NaClO₂), chlorine dioxide (ClO₂), chlorine (Cl₂), or any combination thereof, The method according to claim 1. **Claim 14**: After said step (d), the non-planar three-dimensional configuration is formed to have a repeating undulating configuration formed by being folded or bent multiple times, the undulating configuration having a repeating pattern including at least one peak and at least one valley, the method further includes joining the rigid monolithic fragment of the partially delignified cellulosic material to a first support plate and a second support plate to form a structural material having a honeycomb configuration, the folding or bending in the undulating configuration is about respective axes parallel to a first direction, the first and second support plates are disposed on both sides of the rigid monolithic fragment of the partially delignified cellulosic material with respect to the first direction so as to sandwich the rigid monolithic fragment of the partially delignified cellulosic material, The method according to claim 1.. **Claim 15**: The formation in said step (c) and the further drying in said step (d) are performed simultaneously, The method according to claim 1. **Claim 16**: The further drying in step (d) includes drying and densifying the fragments of the partially delignified cellulosic material using heat pressing. The method according to claim 1. **Claim 17**: A structure formed according to any one of claims 1 to 16.

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